diff --git a/wcfsetup/install/files/lib/system/message/embedded/object/MediaMessageEmbeddedObjectHandler.class.php b/wcfsetup/install/files/lib/system/message/embedded/object/MediaMessageEmbeddedObjectHandler.class.php
index 0b80f406ead..78b98afa745 100644
--- a/wcfsetup/install/files/lib/system/message/embedded/object/MediaMessageEmbeddedObjectHandler.class.php
+++ b/wcfsetup/install/files/lib/system/message/embedded/object/MediaMessageEmbeddedObjectHandler.class.php
@@ -38,7 +38,7 @@ public function parse(HtmlInputProcessor $htmlInputProcessor, array $embeddedDat
             }
         }
 
-        return $mediaIDs;
+        return \array_unique($mediaIDs);
     }
 
     /**
diff --git a/wcfsetup/install/files/lib/system/message/embedded/object/UnfurlUrlEmbeddedObjectHandler.class.php b/wcfsetup/install/files/lib/system/message/embedded/object/UnfurlUrlEmbeddedObjectHandler.class.php
index 8ca51145dea..1260dcf3792 100644
--- a/wcfsetup/install/files/lib/system/message/embedded/object/UnfurlUrlEmbeddedObjectHandler.class.php
+++ b/wcfsetup/install/files/lib/system/message/embedded/object/UnfurlUrlEmbeddedObjectHandler.class.php
@@ -44,6 +44,6 @@ public function parse(HtmlInputProcessor $htmlInputProcessor, array $embeddedDat
             }
         }
 
-        return $unfurlUrlIDs;
+        return \array_unique($unfurlUrlIDs);
     }
 }