diff --git a/osm_nbi/admin_topics.py b/osm_nbi/admin_topics.py
index 0803ad602ad37e7e2a68abb6143011b376483689..b4f89809024be856c2f705842aefae0f04861b4f 100644
--- a/osm_nbi/admin_topics.py
+++ b/osm_nbi/admin_topics.py
@@ -1159,6 +1159,15 @@ class UserTopicAuth(UserTopic):
 
             # set
             if indata.get("project_role_mappings"):
+                duplicates = []
+                for pr in indata.get("project_role_mappings"):
+                    if pr not in duplicates:
+                        duplicates.append(pr)
+                if len(indata.get("project_role_mappings")) > len(duplicates):
+                    raise EngineException(
+                        "Project-role combination should not be repeated",
+                        http_code=HTTPStatus.UNPROCESSABLE_ENTITY,
+                    )
                 for to_set in indata["project_role_mappings"]:
                     for mapping in original_mapping:
                         if to_set["project"] in (