diff --git a/litellm/proxy/management_endpoints/team_endpoints.py b/litellm/proxy/management_endpoints/team_endpoints.py
index a1e96610a56..3d15a855ccf 100644
--- a/litellm/proxy/management_endpoints/team_endpoints.py
+++ b/litellm/proxy/management_endpoints/team_endpoints.py
@@ -964,7 +964,6 @@ def team_member_add_duplication_check(
     invalid_team_members = []
 
     def _check_member_duplication(member: Member):
-        # Check by user_id if provided
         if member.user_id is not None:
             for existing_member in existing_team_row.members_with_roles:
                 if existing_member.user_id == member.user_id:
@@ -976,18 +975,26 @@ def team_member_add_duplication_check(
                 if existing_member.user_email == member.user_email:
                     invalid_team_members.append(member)
 
+    # First, populate the invalid_team_members list by checking for duplicates
+    if isinstance(data.member, Member):
+        _check_member_duplication(data.member)
+    elif isinstance(data.member, List):
+        for m in data.member:
+            _check_member_duplication(m)
+
+    # Then check the populated list and raise exceptions if needed
     if isinstance(data.member, list) and len(invalid_team_members) == len(data.member):
         raise ProxyException(
             message=f"All users are already in team. Existing members={existing_team_row.members_with_roles}",
             type=ProxyErrorTypes.team_member_already_in_team,
-            param="user_email",
+            param="member",
             code="400",
         )
     elif isinstance(data.member, Member) and len(invalid_team_members) == 1:
         raise ProxyException(
-            message=f"User with user_email={data.member.user_email} already in team. Existing members={existing_team_row.members_with_roles}",
+            message=f"User already in team. Member: user_id={data.member.user_id}, user_email={data.member.user_email}. Existing members={existing_team_row.members_with_roles}",
             type=ProxyErrorTypes.team_member_already_in_team,
-            param="user_email",
+            param="member",
             code="400",
         )
     elif len(invalid_team_members) > 0:
@@ -995,12 +1002,6 @@ def team_member_add_duplication_check(
             f"Some users are already in team. Existing members={existing_team_row.members_with_roles}. Duplicate members={invalid_team_members}",
         )
 
-    if isinstance(data.member, Member):
-        _check_member_duplication(data.member)
-    elif isinstance(data.member, List):
-        for m in data.member:
-            _check_member_duplication(m)
-
 
 async def _validate_team_member_add_permissions(
     user_api_key_dict: UserAPIKeyAuth,
diff --git a/tests/test_litellm/proxy/management_endpoints/test_team_endpoints.py b/tests/test_litellm/proxy/management_endpoints/test_team_endpoints.py
index 820d8bd76de..a8c82b4f9b0 100644
--- a/tests/test_litellm/proxy/management_endpoints/test_team_endpoints.py
+++ b/tests/test_litellm/proxy/management_endpoints/test_team_endpoints.py
@@ -561,7 +561,7 @@ def test_team_member_add_duplication_check_raises_proxy_exception():
 
     # Verify the exception details
     assert exc_info.value.type == ProxyErrorTypes.team_member_already_in_team
-    assert exc_info.value.param == "user_id"
+    assert exc_info.value.param == "member"
     assert exc_info.value.code == "400"
     assert "existing-user-id" in str(exc_info.value.message)
     assert "already in team" in str(exc_info.value.message)