diff --git a/fastapi/openapi/utils.py b/fastapi/openapi/utils.py
index dbc93d289..e7e6da2f7 100644
--- a/fastapi/openapi/utils.py
+++ b/fastapi/openapi/utils.py
@@ -79,7 +79,8 @@ def get_openapi_security_definitions(
     flat_dependant: Dependant,
 ) -> Tuple[Dict[str, Any], List[Dict[str, Any]]]:
     security_definitions = {}
-    operation_security = []
+    # Use a dict to merge scopes for same security scheme
+    operation_security_dict: Dict[str, List[str]] = {}
     for security_requirement in flat_dependant.security_requirements:
         security_definition = jsonable_encoder(
             security_requirement.security_scheme.model,
@@ -88,7 +89,15 @@ def get_openapi_security_definitions(
         )
         security_name = security_requirement.security_scheme.scheme_name
         security_definitions[security_name] = security_definition
-        operation_security.append({security_name: security_requirement.scopes})
+        # Merge scopes for the same security scheme
+        if security_name not in operation_security_dict:
+            operation_security_dict[security_name] = []
+        for scope in security_requirement.scopes or []:
+            if scope not in operation_security_dict[security_name]:
+                operation_security_dict[security_name].append(scope)
+    operation_security = [
+        {name: scopes} for name, scopes in operation_security_dict.items()
+    ]
     return security_definitions, operation_security