diff --git a/src/backend/catalog/aclchk.c b/src/backend/catalog/aclchk.c
index 55b0802daff..e7562df6060 100644
--- a/src/backend/catalog/aclchk.c
+++ b/src/backend/catalog/aclchk.c
@@ -1293,6 +1293,9 @@ SetDefaultACL(InternalDefaultACL *iacls)
 		ReleaseSysCache(tuple);
 
 	heap_close(rel, RowExclusiveLock);
+
+	/* prevent error when processing duplicate objects */
+	CommandCounterIncrement();
 }
 
 
diff --git a/src/test/regress/expected/privileges.out b/src/test/regress/expected/privileges.out
index c1936bda092..684e462ffe9 100644
--- a/src/test/regress/expected/privileges.out
+++ b/src/test/regress/expected/privileges.out
@@ -1563,7 +1563,8 @@ SELECT has_table_privilege('regressuser1', 'testns.acltest1', 'INSERT'); -- no
  f
 (1 row)
 
-ALTER DEFAULT PRIVILEGES IN SCHEMA testns GRANT SELECT ON TABLES TO public;
+-- placeholder for test with duplicated schema and role names
+ALTER DEFAULT PRIVILEGES IN SCHEMA testns,testns GRANT SELECT ON TABLES TO public,public;
 SELECT has_table_privilege('regressuser1', 'testns.acltest1', 'SELECT'); -- no
  has_table_privilege 
 ---------------------
diff --git a/src/test/regress/sql/privileges.sql b/src/test/regress/sql/privileges.sql
index 6e9db844ad4..0351f60001a 100644
--- a/src/test/regress/sql/privileges.sql
+++ b/src/test/regress/sql/privileges.sql
@@ -933,7 +933,8 @@ CREATE TABLE testns.acltest1 (x int);
 SELECT has_table_privilege('regressuser1', 'testns.acltest1', 'SELECT'); -- no
 SELECT has_table_privilege('regressuser1', 'testns.acltest1', 'INSERT'); -- no
 
-ALTER DEFAULT PRIVILEGES IN SCHEMA testns GRANT SELECT ON TABLES TO public;
+-- placeholder for test with duplicated schema and role names
+ALTER DEFAULT PRIVILEGES IN SCHEMA testns,testns GRANT SELECT ON TABLES TO public,public;
 
 SELECT has_table_privilege('regressuser1', 'testns.acltest1', 'SELECT'); -- no
 SELECT has_table_privilege('regressuser1', 'testns.acltest1', 'INSERT'); -- no