diff --git a/framework/core/js/forum/src/components/post-stream.js b/framework/core/js/forum/src/components/post-stream.js
index d92229710..61996411b 100644
--- a/framework/core/js/forum/src/components/post-stream.js
+++ b/framework/core/js/forum/src/components/post-stream.js
@@ -88,7 +88,7 @@ class PostStream extends mixin(Component, evented) {
     stream is not visible.
    */
   pushPost(post) {
-    if (this.visibleEnd >= this.count() - 1) {
+    if (this.visibleEnd >= this.count() - 1 && this.posts.indexOf(post) === -1) {
       this.posts.push(post);
       this.visibleEnd++;
     }
diff --git a/framework/core/js/lib/models/discussion.js b/framework/core/js/lib/models/discussion.js
index ed2cdbeaf..20dee1926 100644
--- a/framework/core/js/lib/models/discussion.js
+++ b/framework/core/js/lib/models/discussion.js
@@ -17,7 +17,11 @@ class Discussion extends Model {
       }
 
       if (newData.links && newData.links.addedPosts) {
-        [].push.apply(posts.linkage, newData.links.addedPosts.linkage);
+        newData.links.addedPosts.linkage.forEach(linkage => {
+          if (posts.linkage[posts.linkage.length - 1].id != linkage.id) {
+            posts.linkage.push(linkage);
+          }
+        });
       }
     }
   }