diff --git a/src/backend/catalog/aclchk.c b/src/backend/catalog/aclchk.c
index 1a81e768ec..f3c1ca18ae 100644
--- a/src/backend/catalog/aclchk.c
+++ b/src/backend/catalog/aclchk.c
@@ -1365,6 +1365,9 @@ SetDefaultACL(InternalDefaultACL *iacls)
 		ReleaseSysCache(tuple);
 
 	table_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 7754c20db4..5e5f98ac68 100644
--- a/src/test/regress/expected/privileges.out
+++ b/src/test/regress/expected/privileges.out
@@ -1649,7 +1649,8 @@ SELECT has_table_privilege('regress_priv_user1', 'testns.acltest1', 'INSERT'); -
  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('regress_priv_user1', 'testns.acltest1', 'SELECT'); -- no
  has_table_privilege 
 ---------------------
diff --git a/src/test/regress/sql/privileges.sql b/src/test/regress/sql/privileges.sql
index 4911ad4add..fff76e0bd0 100644
--- a/src/test/regress/sql/privileges.sql
+++ b/src/test/regress/sql/privileges.sql
@@ -985,7 +985,8 @@ CREATE TABLE testns.acltest1 (x int);
 SELECT has_table_privilege('regress_priv_user1', 'testns.acltest1', 'SELECT'); -- no
 SELECT has_table_privilege('regress_priv_user1', '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('regress_priv_user1', 'testns.acltest1', 'SELECT'); -- no
 SELECT has_table_privilege('regress_priv_user1', 'testns.acltest1', 'INSERT'); -- no