diff --git a/backend/open_webui/apps/webui/models/chats.py b/backend/open_webui/apps/webui/models/chats.py
index 9032d2e35..15501e49a 100644
--- a/backend/open_webui/apps/webui/models/chats.py
+++ b/backend/open_webui/apps/webui/models/chats.py
@@ -561,7 +561,7 @@ class ChatTable:
                 if tag_id not in chat.meta.get("tags", []):
                     chat.meta = {
                         **chat.meta,
-                        "tags": chat.meta.get("tags", []) + [tag_id],
+                        "tags": list(set(chat.meta.get("tags", []) + [tag_id])),
                     }
 
                 db.commit()
@@ -618,7 +618,7 @@ class ChatTable:
                 tags = [tag for tag in tags if tag != tag_id]
                 chat.meta = {
                     **chat.meta,
-                    "tags": tags,
+                    "tags": list(set(tags)),
                 }
                 db.commit()
                 return True
diff --git a/backend/open_webui/migrations/versions/1af9b942657b_migrate_tags.py b/backend/open_webui/migrations/versions/1af9b942657b_migrate_tags.py
index 9d79b5749..8a0ab1b49 100644
--- a/backend/open_webui/migrations/versions/1af9b942657b_migrate_tags.py
+++ b/backend/open_webui/migrations/versions/1af9b942657b_migrate_tags.py
@@ -135,7 +135,7 @@ def upgrade():
                 tags = chat_updates[chat_id]["meta"].get("tags", [])
                 tags.append(tag_name)
 
-                chat_updates[chat_id]["meta"]["tags"] = tags
+                chat_updates[chat_id]["meta"]["tags"] = list(set(tags))
 
     # Update chats based on accumulated changes
     for chat_id, updates in chat_updates.items():