diff --git a/lib/reducers/message-reducer.js b/lib/reducers/message-reducer.js
--- a/lib/reducers/message-reducer.js
+++ b/lib/reducers/message-reducer.js
@@ -1293,19 +1293,28 @@
     let newThreads = threads;
     let newLocal = local;
 
+    // Store message IDs already contained within threads so that we
+    // do not insert duplicates
+    const displayedMessages = new Set();
+    for (const threadID in threads) {
+      for (const msgID of threads[threadID].messageIDs) {
+        displayedMessages.add(msgID);
+      }
+    }
+    const threadIDsNeedResorting = new Set();
     const actionPayloadMessages = translateClientDBMessageInfosToRawMessageInfos(
       action.payload,
     );
-    const messageIDsToBeRemoved = [];
 
+    const messageIDsToBeRemoved = [];
     for (const id in actionPayloadMessages) {
       const message = actionPayloadMessages[id];
+      const { threadID } = message;
       if (
         (message.type === messageTypes.IMAGES ||
           message.type === messageTypes.MULTIMEDIA) &&
         !message.id
       ) {
-        const { threadID } = message;
         messageIDsToBeRemoved.push(id);
         newThreads = {
           ...newThreads,
@@ -1319,9 +1328,24 @@
         newLocal = _pickBy(
           (localInfo: LocalMessageInfo, key: string) => key !== id,
         )(newLocal);
+      } else if (!displayedMessages.has(id)) {
+        newThreads = {
+          ...newThreads,
+          [threadID]: {
+            ...newThreads[threadID],
+            messageIDs: [...newThreads[threadID].messageIDs, id],
+          },
+        };
+        threadIDsNeedResorting.add(threadID);
       }
     }
 
+    for (const threadID of threadIDsNeedResorting) {
+      newThreads[threadID].messageIDs = sortMessageIDs(actionPayloadMessages)(
+        newThreads[threadID].messageIDs,
+      );
+    }
+
     messageStore = {
       ...messageStore,
       messages: actionPayloadMessages,