diff --git a/backend/open_webui/models/groups.py b/backend/open_webui/models/groups.py
index cde336bb7b..4c636b4f0f 100644
--- a/backend/open_webui/models/groups.py
+++ b/backend/open_webui/models/groups.py
@@ -290,10 +290,11 @@ class GroupTable:
                     return None
 
                 group_user_ids = group.user_ids
-
                 if not group_user_ids or not isinstance(group_user_ids, list):
                     group_user_ids = []
 
+                group_user_ids = list(set(group_user_ids))  # Deduplicate
+
                 for user_id in user_ids:
                     if user_id not in group_user_ids:
                         group_user_ids.append(user_id)
@@ -321,6 +322,8 @@ class GroupTable:
                 if not group_user_ids or not isinstance(group_user_ids, list):
                     return GroupModel.model_validate(group)
 
+                group_user_ids = list(set(group_user_ids))  # Deduplicate
+
                 for user_id in user_ids:
                     if user_id in group_user_ids:
                         group_user_ids.remove(user_id)