diff --git a/spec/renderer/unit/store/TimelineSpace/Contents/DirectMessages.spec.ts b/spec/renderer/unit/store/TimelineSpace/Contents/DirectMessages.spec.ts
index d976ecaa..fa0c5249 100644
--- a/spec/renderer/unit/store/TimelineSpace/Contents/DirectMessages.spec.ts
+++ b/spec/renderer/unit/store/TimelineSpace/Contents/DirectMessages.spec.ts
@@ -85,6 +85,38 @@ const status2: Status = {
   pinned: null
 }
 
+const rebloggedStatus: Status = {
+  id: '3',
+  uri: 'http://example.com',
+  url: 'http://example.com',
+  account: account,
+  in_reply_to_id: null,
+  in_reply_to_account_id: null,
+  reblog: status1,
+  content: '',
+  created_at: '2019-03-31T21:40:32',
+  emojis: [],
+  replies_count: 0,
+  reblogs_count: 0,
+  favourites_count: 0,
+  reblogged: null,
+  favourited: null,
+  muted: null,
+  sensitive: false,
+  spoiler_text: '',
+  visibility: 'public',
+  media_attachments: [],
+  mentions: [],
+  tags: [],
+  card: null,
+  poll: null,
+  application: {
+    name: 'Web'
+  } as Application,
+  language: null,
+  pinned: null
+}
+
 describe('TimelineSpace/Contents/DirectMessages', () => {
   describe('mutations', () => {
     let state: DirectMessagesState
@@ -108,37 +140,6 @@ describe('TimelineSpace/Contents/DirectMessages', () => {
 
       describe('message is reblogged', () => {
         beforeEach(() => {
-          const rebloggedStatus: Status = {
-            id: '3',
-            uri: 'http://example.com',
-            url: 'http://example.com',
-            account: account,
-            in_reply_to_id: null,
-            in_reply_to_account_id: null,
-            reblog: status1,
-            content: '',
-            created_at: '2019-03-31T21:40:32',
-            emojis: [],
-            replies_count: 0,
-            reblogs_count: 0,
-            favourites_count: 0,
-            reblogged: null,
-            favourited: null,
-            muted: null,
-            sensitive: false,
-            spoiler_text: '',
-            visibility: 'public',
-            media_attachments: [],
-            mentions: [],
-            tags: [],
-            card: null,
-            poll: null,
-            application: {
-              name: 'Web'
-            } as Application,
-            language: null,
-            pinned: null
-          }
           state = {
             lazyLoading: false,
             heading: true,
@@ -153,5 +154,79 @@ describe('TimelineSpace/Contents/DirectMessages', () => {
         })
       })
     })
+
+    describe('appendTimeline', () => {
+      describe('heading', () => {
+        describe('normal', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: true,
+              timeline: [status2, status1],
+              unreadTimeline: [],
+              filter: ''
+            }
+          })
+          it('should be updated timeline', () => {
+            DirectMessages.mutations![MUTATION_TYPES.APPEND_TIMELINE](state, rebloggedStatus)
+            expect(state.timeline).toEqual([rebloggedStatus, status2, status1])
+            expect(state.unreadTimeline).toEqual([])
+          })
+        })
+
+        describe('duplicated status', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: true,
+              timeline: [rebloggedStatus, status2, status1],
+              unreadTimeline: [],
+              filter: ''
+            }
+          })
+          it('should not be updated timeline', () => {
+            DirectMessages.mutations![MUTATION_TYPES.APPEND_TIMELINE](state, rebloggedStatus)
+            expect(state.timeline).toEqual([rebloggedStatus, status2, status1])
+            expect(state.unreadTimeline).toEqual([])
+          })
+        })
+      })
+
+      describe('not heading', () => {
+        describe('normal', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: false,
+              timeline: [status2, status1],
+              unreadTimeline: [],
+              filter: ''
+            }
+          })
+          it('should be updated timeline', () => {
+            DirectMessages.mutations![MUTATION_TYPES.APPEND_TIMELINE](state, rebloggedStatus)
+            expect(state.timeline).toEqual([status2, status1])
+            expect(state.unreadTimeline).toEqual([rebloggedStatus])
+          })
+        })
+
+        describe('duplicated status', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: false,
+              timeline: [rebloggedStatus, status2, status1],
+              unreadTimeline: [],
+              filter: ''
+            }
+          })
+          it('should not be updated timeline', () => {
+            DirectMessages.mutations![MUTATION_TYPES.APPEND_TIMELINE](state, rebloggedStatus)
+            expect(state.timeline).toEqual([rebloggedStatus, status2, status1])
+            expect(state.unreadTimeline).toEqual([])
+          })
+        })
+      })
+    })
   })
 })
diff --git a/spec/renderer/unit/store/TimelineSpace/Contents/Hashtag/Tag.spec.ts b/spec/renderer/unit/store/TimelineSpace/Contents/Hashtag/Tag.spec.ts
index e5151fbc..e05edaed 100644
--- a/spec/renderer/unit/store/TimelineSpace/Contents/Hashtag/Tag.spec.ts
+++ b/spec/renderer/unit/store/TimelineSpace/Contents/Hashtag/Tag.spec.ts
@@ -85,6 +85,38 @@ const status2: Status = {
   pinned: null
 }
 
+const rebloggedStatus: Status = {
+  id: '3',
+  uri: 'http://example.com',
+  url: 'http://example.com',
+  account: account,
+  in_reply_to_id: null,
+  in_reply_to_account_id: null,
+  reblog: status1,
+  content: '',
+  created_at: '2019-03-31T21:40:32',
+  emojis: [],
+  replies_count: 0,
+  reblogs_count: 0,
+  favourites_count: 0,
+  reblogged: null,
+  favourited: null,
+  muted: null,
+  sensitive: false,
+  spoiler_text: '',
+  visibility: 'public',
+  media_attachments: [],
+  mentions: [],
+  tags: [],
+  card: null,
+  poll: null,
+  application: {
+    name: 'Web'
+  } as Application,
+  language: null,
+  pinned: null
+}
+
 describe('TimelineSpace/Contents/Hashtag/Tag', () => {
   describe('mutations', () => {
     let state: TagState
@@ -108,37 +140,6 @@ describe('TimelineSpace/Contents/Hashtag/Tag', () => {
 
       describe('message is reblogged', () => {
         beforeEach(() => {
-          const rebloggedStatus: Status = {
-            id: '3',
-            uri: 'http://example.com',
-            url: 'http://example.com',
-            account: account,
-            in_reply_to_id: null,
-            in_reply_to_account_id: null,
-            reblog: status1,
-            content: '',
-            created_at: '2019-03-31T21:40:32',
-            emojis: [],
-            replies_count: 0,
-            reblogs_count: 0,
-            favourites_count: 0,
-            reblogged: null,
-            favourited: null,
-            muted: null,
-            sensitive: false,
-            spoiler_text: '',
-            visibility: 'public',
-            media_attachments: [],
-            mentions: [],
-            tags: [],
-            card: null,
-            poll: null,
-            application: {
-              name: 'Web'
-            } as Application,
-            language: null,
-            pinned: null
-          }
           state = {
             lazyLoading: false,
             heading: true,
@@ -153,5 +154,79 @@ describe('TimelineSpace/Contents/Hashtag/Tag', () => {
         })
       })
     })
+
+    describe('appendTimeline', () => {
+      describe('heading', () => {
+        describe('normal', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: true,
+              timeline: [status2, status1],
+              unreadTimeline: [],
+              filter: ''
+            }
+          })
+          it('should be updated timeline', () => {
+            Tag.mutations![MUTATION_TYPES.APPEND_TIMELINE](state, rebloggedStatus)
+            expect(state.timeline).toEqual([rebloggedStatus, status2, status1])
+            expect(state.unreadTimeline).toEqual([])
+          })
+        })
+
+        describe('duplicated status', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: true,
+              timeline: [rebloggedStatus, status2, status1],
+              unreadTimeline: [],
+              filter: ''
+            }
+          })
+          it('should not be updated timeline', () => {
+            Tag.mutations![MUTATION_TYPES.APPEND_TIMELINE](state, rebloggedStatus)
+            expect(state.timeline).toEqual([rebloggedStatus, status2, status1])
+            expect(state.unreadTimeline).toEqual([])
+          })
+        })
+      })
+
+      describe('not heading', () => {
+        describe('normal', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: false,
+              timeline: [status2, status1],
+              unreadTimeline: [],
+              filter: ''
+            }
+          })
+          it('should be updated timeline', () => {
+            Tag.mutations![MUTATION_TYPES.APPEND_TIMELINE](state, rebloggedStatus)
+            expect(state.timeline).toEqual([status2, status1])
+            expect(state.unreadTimeline).toEqual([rebloggedStatus])
+          })
+        })
+
+        describe('duplicated status', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: false,
+              timeline: [rebloggedStatus, status2, status1],
+              unreadTimeline: [],
+              filter: ''
+            }
+          })
+          it('should not be updated timeline', () => {
+            Tag.mutations![MUTATION_TYPES.APPEND_TIMELINE](state, rebloggedStatus)
+            expect(state.timeline).toEqual([rebloggedStatus, status2, status1])
+            expect(state.unreadTimeline).toEqual([])
+          })
+        })
+      })
+    })
   })
 })
diff --git a/spec/renderer/unit/store/TimelineSpace/Contents/Home.spec.ts b/spec/renderer/unit/store/TimelineSpace/Contents/Home.spec.ts
index 84969ad3..800c9ec4 100644
--- a/spec/renderer/unit/store/TimelineSpace/Contents/Home.spec.ts
+++ b/spec/renderer/unit/store/TimelineSpace/Contents/Home.spec.ts
@@ -116,40 +116,81 @@ describe('TimelineSpace/Contents/Home', () => {
 
     describe('appendTimeline', () => {
       describe('heading', () => {
-        beforeEach(() => {
-          state = {
-            lazyLoading: false,
-            heading: true,
-            timeline: [status1],
-            unreadTimeline: [],
-            filter: '',
-            showReblogs: true,
-            showReplies: true
-          }
+        describe('normal', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: true,
+              timeline: [status1],
+              unreadTimeline: [],
+              filter: '',
+              showReblogs: true,
+              showReplies: true
+            }
+          })
+          it('should update timeline', () => {
+            Home.mutations![MUTATION_TYPES.APPEND_TIMELINE](state, status2)
+            expect(state.timeline).toEqual([status2, status1])
+            expect(state.unreadTimeline).toEqual([])
+          })
         })
-        it('should update timeline', () => {
-          Home.mutations![MUTATION_TYPES.APPEND_TIMELINE](state, status2)
-          expect(state.timeline).toEqual([status2, status1])
-          expect(state.unreadTimeline).toEqual([])
+
+        describe('duplicated status', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: true,
+              timeline: [status2, status1],
+              unreadTimeline: [],
+              filter: '',
+              showReblogs: true,
+              showReplies: true
+            }
+          })
+          it('should not update timeline', () => {
+            Home.mutations![MUTATION_TYPES.APPEND_TIMELINE](state, status2)
+            expect(state.timeline).toEqual([status2, status1])
+            expect(state.unreadTimeline).toEqual([])
+          })
         })
       })
 
       describe('not heading', () => {
-        beforeEach(() => {
-          state = {
-            lazyLoading: false,
-            heading: false,
-            timeline: [status1],
-            unreadTimeline: [],
-            filter: '',
-            showReblogs: true,
-            showReplies: true
-          }
+        describe('normal', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: false,
+              timeline: [status1],
+              unreadTimeline: [],
+              filter: '',
+              showReblogs: true,
+              showReplies: true
+            }
+          })
+          it('should update unreadTimeline', () => {
+            Home.mutations![MUTATION_TYPES.APPEND_TIMELINE](state, status2)
+            expect(state.timeline).toEqual([status1])
+            expect(state.unreadTimeline).toEqual([status2])
+          })
         })
-        it('should update unreadTimeline', () => {
-          Home.mutations![MUTATION_TYPES.APPEND_TIMELINE](state, status2)
-          expect(state.timeline).toEqual([status1])
-          expect(state.unreadTimeline).toEqual([status2])
+        describe('duplicated status', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: false,
+              timeline: [],
+              unreadTimeline: [status2, status1],
+              filter: '',
+              showReblogs: true,
+              showReplies: true
+            }
+          })
+          it('should not update unreadTimeline', () => {
+            Home.mutations![MUTATION_TYPES.APPEND_TIMELINE](state, status2)
+            expect(state.timeline).toEqual([])
+            expect(state.unreadTimeline).toEqual([status2, status1])
+          })
         })
       })
     })
diff --git a/spec/renderer/unit/store/TimelineSpace/Contents/Lists/Show.spec.ts b/spec/renderer/unit/store/TimelineSpace/Contents/Lists/Show.spec.ts
index 5781a43d..bae785cb 100644
--- a/spec/renderer/unit/store/TimelineSpace/Contents/Lists/Show.spec.ts
+++ b/spec/renderer/unit/store/TimelineSpace/Contents/Lists/Show.spec.ts
@@ -85,6 +85,38 @@ const status2: Status = {
   pinned: null
 }
 
+const rebloggedStatus: Status = {
+  id: '3',
+  uri: 'http://example.com',
+  url: 'http://example.com',
+  account: account,
+  in_reply_to_id: null,
+  in_reply_to_account_id: null,
+  reblog: status1,
+  content: '',
+  created_at: '2019-03-31T21:40:32',
+  emojis: [],
+  replies_count: 0,
+  reblogs_count: 0,
+  favourites_count: 0,
+  reblogged: null,
+  favourited: null,
+  muted: null,
+  sensitive: false,
+  spoiler_text: '',
+  visibility: 'public',
+  media_attachments: [],
+  mentions: [],
+  tags: [],
+  card: null,
+  poll: null,
+  application: {
+    name: 'Web'
+  } as Application,
+  language: null,
+  pinned: null
+}
+
 describe('TimelineSpace/Contents/Lists/Show', () => {
   describe('mutations', () => {
     let state: ShowState
@@ -108,37 +140,6 @@ describe('TimelineSpace/Contents/Lists/Show', () => {
 
       describe('message is reblogged', () => {
         beforeEach(() => {
-          const rebloggedStatus: Status = {
-            id: '3',
-            uri: 'http://example.com',
-            url: 'http://example.com',
-            account: account,
-            in_reply_to_id: null,
-            in_reply_to_account_id: null,
-            reblog: status1,
-            content: '',
-            created_at: '2019-03-31T21:40:32',
-            emojis: [],
-            replies_count: 0,
-            reblogs_count: 0,
-            favourites_count: 0,
-            reblogged: null,
-            favourited: null,
-            muted: null,
-            sensitive: false,
-            spoiler_text: '',
-            visibility: 'public',
-            media_attachments: [],
-            mentions: [],
-            tags: [],
-            card: null,
-            poll: null,
-            application: {
-              name: 'Web'
-            } as Application,
-            language: null,
-            pinned: null
-          }
           state = {
             lazyLoading: false,
             heading: true,
@@ -153,5 +154,79 @@ describe('TimelineSpace/Contents/Lists/Show', () => {
         })
       })
     })
+
+    describe('appendTimeline', () => {
+      describe('heading', () => {
+        describe('normal', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: true,
+              timeline: [status2, status1],
+              unreadTimeline: [],
+              filter: ''
+            }
+          })
+          it('should be updated timeline', () => {
+            Show.mutations![MUTATION_TYPES.APPEND_TIMELINE](state, rebloggedStatus)
+            expect(state.timeline).toEqual([rebloggedStatus, status2, status1])
+            expect(state.unreadTimeline).toEqual([])
+          })
+        })
+
+        describe('duplicated status', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: true,
+              timeline: [rebloggedStatus, status2, status1],
+              unreadTimeline: [],
+              filter: ''
+            }
+          })
+          it('should not be updated timeline', () => {
+            Show.mutations![MUTATION_TYPES.APPEND_TIMELINE](state, rebloggedStatus)
+            expect(state.timeline).toEqual([rebloggedStatus, status2, status1])
+            expect(state.unreadTimeline).toEqual([])
+          })
+        })
+      })
+
+      describe('not heading', () => {
+        describe('normal', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: false,
+              timeline: [status2, status1],
+              unreadTimeline: [],
+              filter: ''
+            }
+          })
+          it('should be updated timeline', () => {
+            Show.mutations![MUTATION_TYPES.APPEND_TIMELINE](state, rebloggedStatus)
+            expect(state.timeline).toEqual([status2, status1])
+            expect(state.unreadTimeline).toEqual([rebloggedStatus])
+          })
+        })
+
+        describe('duplicated status', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: false,
+              timeline: [rebloggedStatus, status2, status1],
+              unreadTimeline: [],
+              filter: ''
+            }
+          })
+          it('should not be updated timeline', () => {
+            Show.mutations![MUTATION_TYPES.APPEND_TIMELINE](state, rebloggedStatus)
+            expect(state.timeline).toEqual([rebloggedStatus, status2, status1])
+            expect(state.unreadTimeline).toEqual([])
+          })
+        })
+      })
+    })
   })
 })
diff --git a/spec/renderer/unit/store/TimelineSpace/Contents/Local.spec.ts b/spec/renderer/unit/store/TimelineSpace/Contents/Local.spec.ts
index 10dc8fa9..899eb185 100644
--- a/spec/renderer/unit/store/TimelineSpace/Contents/Local.spec.ts
+++ b/spec/renderer/unit/store/TimelineSpace/Contents/Local.spec.ts
@@ -85,6 +85,38 @@ const status2: Status = {
   pinned: null
 }
 
+const rebloggedStatus: Status = {
+  id: '3',
+  uri: 'http://example.com',
+  url: 'http://example.com',
+  account: account,
+  in_reply_to_id: null,
+  in_reply_to_account_id: null,
+  reblog: status1,
+  content: '',
+  created_at: '2019-03-31T21:40:32',
+  emojis: [],
+  replies_count: 0,
+  reblogs_count: 0,
+  favourites_count: 0,
+  reblogged: null,
+  favourited: null,
+  muted: null,
+  sensitive: false,
+  spoiler_text: '',
+  visibility: 'public',
+  media_attachments: [],
+  mentions: [],
+  tags: [],
+  card: null,
+  poll: null,
+  application: {
+    name: 'Web'
+  } as Application,
+  language: null,
+  pinned: null
+}
+
 describe('TimelineSpace/Contents/Local', () => {
   describe('mutations', () => {
     let state: LocalState
@@ -108,37 +140,6 @@ describe('TimelineSpace/Contents/Local', () => {
 
       describe('message is reblogged', () => {
         beforeEach(() => {
-          const rebloggedStatus: Status = {
-            id: '3',
-            uri: 'http://example.com',
-            url: 'http://example.com',
-            account: account,
-            in_reply_to_id: null,
-            in_reply_to_account_id: null,
-            reblog: status1,
-            content: '',
-            created_at: '2019-03-31T21:40:32',
-            emojis: [],
-            replies_count: 0,
-            reblogs_count: 0,
-            favourites_count: 0,
-            reblogged: null,
-            favourited: null,
-            muted: null,
-            sensitive: false,
-            spoiler_text: '',
-            visibility: 'public',
-            media_attachments: [],
-            mentions: [],
-            tags: [],
-            card: null,
-            poll: null,
-            application: {
-              name: 'Web'
-            } as Application,
-            language: null,
-            pinned: null
-          }
           state = {
             lazyLoading: false,
             heading: true,
@@ -153,5 +154,78 @@ describe('TimelineSpace/Contents/Local', () => {
         })
       })
     })
+    describe('appendTimeline', () => {
+      describe('heading', () => {
+        describe('normal', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: true,
+              timeline: [status2, status1],
+              unreadTimeline: [],
+              filter: ''
+            }
+          })
+          it('should be updated timeline', () => {
+            Local.mutations![MUTATION_TYPES.APPEND_TIMELINE](state, rebloggedStatus)
+            expect(state.timeline).toEqual([rebloggedStatus, status2, status1])
+            expect(state.unreadTimeline).toEqual([])
+          })
+        })
+
+        describe('duplicated status', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: true,
+              timeline: [rebloggedStatus, status2, status1],
+              unreadTimeline: [],
+              filter: ''
+            }
+          })
+          it('should not be updated timeline', () => {
+            Local.mutations![MUTATION_TYPES.APPEND_TIMELINE](state, rebloggedStatus)
+            expect(state.timeline).toEqual([rebloggedStatus, status2, status1])
+            expect(state.unreadTimeline).toEqual([])
+          })
+        })
+      })
+
+      describe('not heading', () => {
+        describe('normal', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: false,
+              timeline: [status2, status1],
+              unreadTimeline: [],
+              filter: ''
+            }
+          })
+          it('should be updated timeline', () => {
+            Local.mutations![MUTATION_TYPES.APPEND_TIMELINE](state, rebloggedStatus)
+            expect(state.timeline).toEqual([status2, status1])
+            expect(state.unreadTimeline).toEqual([rebloggedStatus])
+          })
+        })
+
+        describe('duplicated status', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: false,
+              timeline: [rebloggedStatus, status2, status1],
+              unreadTimeline: [],
+              filter: ''
+            }
+          })
+          it('should not be updated timeline', () => {
+            Local.mutations![MUTATION_TYPES.APPEND_TIMELINE](state, rebloggedStatus)
+            expect(state.timeline).toEqual([rebloggedStatus, status2, status1])
+            expect(state.unreadTimeline).toEqual([])
+          })
+        })
+      })
+    })
   })
 })
diff --git a/spec/renderer/unit/store/TimelineSpace/Contents/Mentions.spec.ts b/spec/renderer/unit/store/TimelineSpace/Contents/Mentions.spec.ts
index 57abf3c2..eff364f1 100644
--- a/spec/renderer/unit/store/TimelineSpace/Contents/Mentions.spec.ts
+++ b/spec/renderer/unit/store/TimelineSpace/Contents/Mentions.spec.ts
@@ -172,35 +172,74 @@ describe('TimelineSpace/Contents/Mentions', () => {
 
     describe('appendMentions', () => {
       describe('heading', () => {
-        beforeEach(() => {
-          state = {
-            lazyLoading: false,
-            heading: true,
-            mentions: [notification1],
-            unreadMentions: [],
-            filter: ''
-          }
+        describe('normal', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: true,
+              mentions: [notification1],
+              unreadMentions: [],
+              filter: ''
+            }
+          })
+          it('should update mentions', () => {
+            Mentions.mutations![MUTATION_TYPES.APPEND_MENTIONS](state, notification2)
+            expect(state.mentions).toEqual([notification2, notification1])
+            expect(state.unreadMentions).toEqual([])
+          })
         })
-        it('should update mentions', () => {
-          Mentions.mutations![MUTATION_TYPES.APPEND_MENTIONS](state, notification2)
-          expect(state.mentions).toEqual([notification2, notification1])
-          expect(state.unreadMentions).toEqual([])
+
+        describe('duplicated status', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: true,
+              mentions: [notification2, notification1],
+              unreadMentions: [],
+              filter: ''
+            }
+          })
+          it('should not be updated mentions', () => {
+            Mentions.mutations![MUTATION_TYPES.APPEND_MENTIONS](state, notification2)
+            expect(state.mentions).toEqual([notification2, notification1])
+            expect(state.unreadMentions).toEqual([])
+          })
         })
       })
+
       describe('not heading', () => {
-        beforeEach(() => {
-          state = {
-            lazyLoading: false,
-            heading: false,
-            mentions: [notification1],
-            unreadMentions: [],
-            filter: ''
-          }
+        describe('normal', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: false,
+              mentions: [notification1],
+              unreadMentions: [],
+              filter: ''
+            }
+          })
+          it('should update mentions', () => {
+            Mentions.mutations![MUTATION_TYPES.APPEND_MENTIONS](state, notification2)
+            expect(state.mentions).toEqual([notification1])
+            expect(state.unreadMentions).toEqual([notification2])
+          })
         })
-        it('should update mentions', () => {
-          Mentions.mutations![MUTATION_TYPES.APPEND_MENTIONS](state, notification2)
-          expect(state.mentions).toEqual([notification1])
-          expect(state.unreadMentions).toEqual([notification2])
+
+        describe('duplicated status', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: false,
+              mentions: [notification1],
+              unreadMentions: [notification2],
+              filter: ''
+            }
+          })
+          it('should not be updated mentions', () => {
+            Mentions.mutations![MUTATION_TYPES.APPEND_MENTIONS](state, notification2)
+            expect(state.mentions).toEqual([notification1])
+            expect(state.unreadMentions).toEqual([notification2])
+          })
         })
       })
     })
diff --git a/spec/renderer/unit/store/TimelineSpace/Contents/Notifications.spec.ts b/spec/renderer/unit/store/TimelineSpace/Contents/Notifications.spec.ts
index 6a7531ab..99f54e36 100644
--- a/spec/renderer/unit/store/TimelineSpace/Contents/Notifications.spec.ts
+++ b/spec/renderer/unit/store/TimelineSpace/Contents/Notifications.spec.ts
@@ -184,5 +184,78 @@ describe('TimelineSpace/Contents/Notifications', () => {
         })
       })
     })
+
+    describe('appendTimeline', () => {
+      describe('heading', () => {
+        describe('normal', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: true,
+              notifications: [notification1],
+              unreadNotifications: [],
+              filter: ''
+            }
+          })
+          it('should update timeline', () => {
+            Notifications.mutations![MUTATION_TYPES.APPEND_NOTIFICATIONS](state, notification2)
+            expect(state.notifications).toEqual([notification2, notification1])
+            expect(state.unreadNotifications).toEqual([])
+          })
+        })
+
+        describe('duplicated status', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: true,
+              notifications: [notification2, notification1],
+              unreadNotifications: [],
+              filter: ''
+            }
+          })
+          it('should not update timeline', () => {
+            Notifications.mutations![MUTATION_TYPES.APPEND_NOTIFICATIONS](state, notification2)
+            expect(state.notifications).toEqual([notification2, notification1])
+            expect(state.unreadNotifications).toEqual([])
+          })
+        })
+      })
+
+      describe('not heading', () => {
+        describe('normal', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: false,
+              notifications: [notification1],
+              unreadNotifications: [],
+              filter: ''
+            }
+          })
+          it('should update unreadTimeline', () => {
+            Notifications.mutations![MUTATION_TYPES.APPEND_NOTIFICATIONS](state, notification2)
+            expect(state.notifications).toEqual([notification1])
+            expect(state.unreadNotifications).toEqual([notification2])
+          })
+        })
+        describe('duplicated status', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: false,
+              notifications: [notification1],
+              unreadNotifications: [notification2],
+              filter: ''
+            }
+          })
+          it('should not update unreadTimeline', () => {
+            Notifications.mutations![MUTATION_TYPES.APPEND_NOTIFICATIONS](state, notification2)
+            expect(state.notifications).toEqual([notification1])
+            expect(state.unreadNotifications).toEqual([notification2])
+          })
+        })
+      })
+    })
   })
 })
diff --git a/spec/renderer/unit/store/TimelineSpace/Contents/Public.spec.ts b/spec/renderer/unit/store/TimelineSpace/Contents/Public.spec.ts
index 33a3b19b..183cbb4e 100644
--- a/spec/renderer/unit/store/TimelineSpace/Contents/Public.spec.ts
+++ b/spec/renderer/unit/store/TimelineSpace/Contents/Public.spec.ts
@@ -85,6 +85,38 @@ const status2: Status = {
   pinned: null
 }
 
+const rebloggedStatus: Status = {
+  id: '3',
+  uri: 'http://example.com',
+  url: 'http://example.com',
+  account: account,
+  in_reply_to_id: null,
+  in_reply_to_account_id: null,
+  reblog: status1,
+  content: '',
+  created_at: '2019-03-31T21:40:32',
+  emojis: [],
+  replies_count: 0,
+  reblogs_count: 0,
+  favourites_count: 0,
+  reblogged: null,
+  favourited: null,
+  muted: null,
+  sensitive: false,
+  spoiler_text: '',
+  visibility: 'public',
+  media_attachments: [],
+  mentions: [],
+  tags: [],
+  card: null,
+  poll: null,
+  application: {
+    name: 'Web'
+  } as Application,
+  language: null,
+  pinned: null
+}
+
 describe('TimelineSpace/Contents/Local', () => {
   describe('mutations', () => {
     let state: PublicState
@@ -108,37 +140,6 @@ describe('TimelineSpace/Contents/Local', () => {
 
       describe('message is reblogged', () => {
         beforeEach(() => {
-          const rebloggedStatus: Status = {
-            id: '3',
-            uri: 'http://example.com',
-            url: 'http://example.com',
-            account: account,
-            in_reply_to_id: null,
-            in_reply_to_account_id: null,
-            reblog: status1,
-            content: '',
-            created_at: '2019-03-31T21:40:32',
-            emojis: [],
-            replies_count: 0,
-            reblogs_count: 0,
-            favourites_count: 0,
-            reblogged: null,
-            favourited: null,
-            muted: null,
-            sensitive: false,
-            spoiler_text: '',
-            visibility: 'public',
-            media_attachments: [],
-            mentions: [],
-            tags: [],
-            card: null,
-            poll: null,
-            application: {
-              name: 'Web'
-            } as Application,
-            language: null,
-            pinned: null
-          }
           state = {
             lazyLoading: false,
             heading: true,
@@ -153,5 +154,79 @@ describe('TimelineSpace/Contents/Local', () => {
         })
       })
     })
+
+    describe('appendTimeline', () => {
+      describe('heading', () => {
+        describe('normal', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: true,
+              timeline: [status2, status1],
+              unreadTimeline: [],
+              filter: ''
+            }
+          })
+          it('should be updated timeline', () => {
+            Public.mutations![MUTATION_TYPES.APPEND_TIMELINE](state, rebloggedStatus)
+            expect(state.timeline).toEqual([rebloggedStatus, status2, status1])
+            expect(state.unreadTimeline).toEqual([])
+          })
+        })
+
+        describe('duplicated status', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: true,
+              timeline: [rebloggedStatus, status2, status1],
+              unreadTimeline: [],
+              filter: ''
+            }
+          })
+          it('should not be updated timeline', () => {
+            Public.mutations![MUTATION_TYPES.APPEND_TIMELINE](state, rebloggedStatus)
+            expect(state.timeline).toEqual([rebloggedStatus, status2, status1])
+            expect(state.unreadTimeline).toEqual([])
+          })
+        })
+      })
+
+      describe('not heading', () => {
+        describe('normal', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: false,
+              timeline: [status2, status1],
+              unreadTimeline: [],
+              filter: ''
+            }
+          })
+          it('should be updated timeline', () => {
+            Public.mutations![MUTATION_TYPES.APPEND_TIMELINE](state, rebloggedStatus)
+            expect(state.timeline).toEqual([status2, status1])
+            expect(state.unreadTimeline).toEqual([rebloggedStatus])
+          })
+        })
+
+        describe('duplicated status', () => {
+          beforeEach(() => {
+            state = {
+              lazyLoading: false,
+              heading: false,
+              timeline: [rebloggedStatus, status2, status1],
+              unreadTimeline: [],
+              filter: ''
+            }
+          })
+          it('should not be updated timeline', () => {
+            Public.mutations![MUTATION_TYPES.APPEND_TIMELINE](state, rebloggedStatus)
+            expect(state.timeline).toEqual([rebloggedStatus, status2, status1])
+            expect(state.unreadTimeline).toEqual([])
+          })
+        })
+      })
+    })
   })
 })
diff --git a/src/renderer/store/TimelineSpace/Contents/DirectMessages.ts b/src/renderer/store/TimelineSpace/Contents/DirectMessages.ts
index fa6d437f..3a51aa75 100644
--- a/src/renderer/store/TimelineSpace/Contents/DirectMessages.ts
+++ b/src/renderer/store/TimelineSpace/Contents/DirectMessages.ts
@@ -40,10 +40,13 @@ const mutations: MutationTree<DirectMessagesState> = {
     state.heading = value
   },
   [MUTATION_TYPES.APPEND_TIMELINE]: (state, update: Status) => {
-    if (state.heading) {
-      state.timeline = [update].concat(state.timeline)
-    } else {
-      state.unreadTimeline = [update].concat(state.unreadTimeline)
+    // Reject duplicated status in timeline
+    if (!state.timeline.find(item => item.id === update.id) && !state.unreadTimeline.find(item => item.id === update.id)) {
+      if (state.heading) {
+        state.timeline = [update].concat(state.timeline)
+      } else {
+        state.unreadTimeline = [update].concat(state.unreadTimeline)
+      }
     }
   },
   [MUTATION_TYPES.UPDATE_TIMELINE]: (state, messages: Array<Status>) => {
diff --git a/src/renderer/store/TimelineSpace/Contents/Hashtag/Tag.ts b/src/renderer/store/TimelineSpace/Contents/Hashtag/Tag.ts
index e732351f..9bb43811 100644
--- a/src/renderer/store/TimelineSpace/Contents/Hashtag/Tag.ts
+++ b/src/renderer/store/TimelineSpace/Contents/Hashtag/Tag.ts
@@ -39,10 +39,13 @@ const mutations: MutationTree<TagState> = {
     state.heading = value
   },
   [MUTATION_TYPES.APPEND_TIMELINE]: (state, update: Status) => {
-    if (state.heading) {
-      state.timeline = [update].concat(state.timeline)
-    } else {
-      state.unreadTimeline = [update].concat(state.unreadTimeline)
+    // Reject duplicated status in timeline
+    if (!state.timeline.find(item => item.id === update.id) && !state.unreadTimeline.find(item => item.id === update.id)) {
+      if (state.heading) {
+        state.timeline = [update].concat(state.timeline)
+      } else {
+        state.unreadTimeline = [update].concat(state.unreadTimeline)
+      }
     }
   },
   [MUTATION_TYPES.UPDATE_TIMELINE]: (state, timeline: Array<Status>) => {
diff --git a/src/renderer/store/TimelineSpace/Contents/Home.ts b/src/renderer/store/TimelineSpace/Contents/Home.ts
index f2326d7d..5518ab54 100644
--- a/src/renderer/store/TimelineSpace/Contents/Home.ts
+++ b/src/renderer/store/TimelineSpace/Contents/Home.ts
@@ -46,10 +46,13 @@ const mutations: MutationTree<HomeState> = {
     state.heading = value
   },
   [MUTATION_TYPES.APPEND_TIMELINE]: (state, update: Status) => {
-    if (state.heading) {
-      state.timeline = [update].concat(state.timeline)
-    } else {
-      state.unreadTimeline = [update].concat(state.unreadTimeline)
+    // Reject duplicated status in timeline
+    if (!state.timeline.find(item => item.id === update.id) && !state.unreadTimeline.find(item => item.id === update.id)) {
+      if (state.heading) {
+        state.timeline = [update].concat(state.timeline)
+      } else {
+        state.unreadTimeline = [update].concat(state.unreadTimeline)
+      }
     }
   },
   [MUTATION_TYPES.UPDATE_TIMELINE]: (state, messages: Array<Status>) => {
diff --git a/src/renderer/store/TimelineSpace/Contents/Lists/Show.ts b/src/renderer/store/TimelineSpace/Contents/Lists/Show.ts
index cb938e70..78a8adbc 100644
--- a/src/renderer/store/TimelineSpace/Contents/Lists/Show.ts
+++ b/src/renderer/store/TimelineSpace/Contents/Lists/Show.ts
@@ -39,10 +39,13 @@ const mutations: MutationTree<ShowState> = {
     state.heading = value
   },
   [MUTATION_TYPES.APPEND_TIMELINE]: (state, update: Status) => {
-    if (state.heading) {
-      state.timeline = [update].concat(state.timeline)
-    } else {
-      state.unreadTimeline = [update].concat(state.unreadTimeline)
+    // Reject duplicated status in timeline
+    if (!state.timeline.find(item => item.id === update.id) && !state.unreadTimeline.find(item => item.id === update.id)) {
+      if (state.heading) {
+        state.timeline = [update].concat(state.timeline)
+      } else {
+        state.unreadTimeline = [update].concat(state.unreadTimeline)
+      }
     }
   },
   [MUTATION_TYPES.UPDATE_TIMELINE]: (state, timeline: Array<Status>) => {
diff --git a/src/renderer/store/TimelineSpace/Contents/Local.ts b/src/renderer/store/TimelineSpace/Contents/Local.ts
index d773feb0..3e988789 100644
--- a/src/renderer/store/TimelineSpace/Contents/Local.ts
+++ b/src/renderer/store/TimelineSpace/Contents/Local.ts
@@ -37,10 +37,13 @@ const mutations: MutationTree<LocalState> = {
     state.heading = value
   },
   [MUTATION_TYPES.APPEND_TIMELINE]: (state, update: Status) => {
-    if (state.heading) {
-      state.timeline = [update].concat(state.timeline)
-    } else {
-      state.unreadTimeline = [update].concat(state.unreadTimeline)
+    // Reject duplicated status in timeline
+    if (!state.timeline.find(item => item.id === update.id) && !state.unreadTimeline.find(item => item.id === update.id)) {
+      if (state.heading) {
+        state.timeline = [update].concat(state.timeline)
+      } else {
+        state.unreadTimeline = [update].concat(state.unreadTimeline)
+      }
     }
   },
   [MUTATION_TYPES.UPDATE_TIMELINE]: (state, messages: Array<Status>) => {
diff --git a/src/renderer/store/TimelineSpace/Contents/Mentions.ts b/src/renderer/store/TimelineSpace/Contents/Mentions.ts
index ccc8f796..58ace721 100644
--- a/src/renderer/store/TimelineSpace/Contents/Mentions.ts
+++ b/src/renderer/store/TimelineSpace/Contents/Mentions.ts
@@ -40,10 +40,13 @@ const mutations: MutationTree<MentionsState> = {
     state.heading = value
   },
   [MUTATION_TYPES.APPEND_MENTIONS]: (state, update: Notification) => {
-    if (state.heading) {
-      state.mentions = [update].concat(state.mentions)
-    } else {
-      state.unreadMentions = [update].concat(state.unreadMentions)
+    // Reject duplicated status in timeline
+    if (!state.mentions.find(item => item.id === update.id) && !state.unreadMentions.find(item => item.id === update.id)) {
+      if (state.heading) {
+        state.mentions = [update].concat(state.mentions)
+      } else {
+        state.unreadMentions = [update].concat(state.unreadMentions)
+      }
     }
   },
   [MUTATION_TYPES.UPDATE_MENTIONS]: (state, messages: Array<Notification>) => {
diff --git a/src/renderer/store/TimelineSpace/Contents/Notifications.ts b/src/renderer/store/TimelineSpace/Contents/Notifications.ts
index 1225b95e..2e245bbd 100644
--- a/src/renderer/store/TimelineSpace/Contents/Notifications.ts
+++ b/src/renderer/store/TimelineSpace/Contents/Notifications.ts
@@ -41,10 +41,16 @@ const mutations: MutationTree<NotificationsState> = {
     state.heading = value
   },
   [MUTATION_TYPES.APPEND_NOTIFICATIONS]: (state, notification: Notification) => {
-    if (state.heading) {
-      state.notifications = [notification].concat(state.notifications)
-    } else {
-      state.unreadNotifications = [notification].concat(state.unreadNotifications)
+    // Reject duplicated status in timeline
+    if (
+      !state.notifications.find(item => item.id === notification.id) &&
+      !state.unreadNotifications.find(item => item.id === notification.id)
+    ) {
+      if (state.heading) {
+        state.notifications = [notification].concat(state.notifications)
+      } else {
+        state.unreadNotifications = [notification].concat(state.unreadNotifications)
+      }
     }
   },
   [MUTATION_TYPES.UPDATE_NOTIFICATIONS]: (state, notifications: Array<Notification>) => {
diff --git a/src/renderer/store/TimelineSpace/Contents/Public.ts b/src/renderer/store/TimelineSpace/Contents/Public.ts
index db6ece74..92931056 100644
--- a/src/renderer/store/TimelineSpace/Contents/Public.ts
+++ b/src/renderer/store/TimelineSpace/Contents/Public.ts
@@ -37,10 +37,13 @@ const mutations: MutationTree<PublicState> = {
     state.heading = value
   },
   [MUTATION_TYPES.APPEND_TIMELINE]: (state, update: Status) => {
-    if (state.heading) {
-      state.timeline = [update].concat(state.timeline)
-    } else {
-      state.unreadTimeline = [update].concat(state.unreadTimeline)
+    // Reject duplicated status in timeline
+    if (!state.timeline.find(item => item.id === update.id) && !state.unreadTimeline.find(item => item.id === update.id)) {
+      if (state.heading) {
+        state.timeline = [update].concat(state.timeline)
+      } else {
+        state.unreadTimeline = [update].concat(state.unreadTimeline)
+      }
     }
   },
   [MUTATION_TYPES.UPDATE_TIMELINE]: (state, messages: Array<Status>) => {