diff --git a/src/backend/cdb/cdbmutate.c b/src/backend/cdb/cdbmutate.c
index 01744c1058316c1e20a9cb47c44e4cb59f0c75bb..4c5de16fe805e616ecc0d9fb85ef17485622f15d 100644
--- a/src/backend/cdb/cdbmutate.c
+++ b/src/backend/cdb/cdbmutate.c
@@ -351,9 +351,27 @@ apply_motion(PlannerInfo *root, Plan *plan, Query *query)
 					
 									if (equal(var1,new_var))
 									{
+										int i;
+
 										/* If it is, use it to partition the result table, to avoid
 										 * unnecessary redistibution of data */
 										Assert(targetPolicy->nattrs < MaxPolicyAttributeNumber);
+
+										/* check duplicate distribute key */
+										for (i = 0; i < targetPolicy->nattrs; i++)
+										{
+											if (targetPolicy->attrs[i] != n)
+												continue;
+
+											TargetEntry *target = get_tle_by_resno(plan->targetlist, n);
+
+											ereport(ERROR,
+													(errcode(ERRCODE_DUPLICATE_COLUMN),
+													 errmsg("duplicate DISTRIBUTED BY column '%s'",
+															target->resname ? target->resname : "???")));
+
+										}
+
 										targetPolicy->attrs[targetPolicy->nattrs++] = n;
 										found_expr = true;
 										break;
diff --git a/src/test/regress/expected/qp_misc_jiras.out b/src/test/regress/expected/qp_misc_jiras.out
index 94bd4e43eb4aeeaf7dd786d7a7ebe3a2bac91031..5a53509759f4ed3224d59d28983fd94988972bb1 100644
--- a/src/test/regress/expected/qp_misc_jiras.out
+++ b/src/test/regress/expected/qp_misc_jiras.out
@@ -4595,6 +4595,12 @@ select test();
  
 (1 row)
 
+-- Test duplicate distribute keys
+CREATE TABLE qp_misc_jiras.ctas_dup_dk_src (col1 int, col2 int);
+CREATE TABLE qp_misc_jiras.ctas_dup_dk as SELECT distinct col2 as c1, col2 as c2 from qp_misc_jiras.ctas_dup_dk_src;
+ERROR:  duplicate DISTRIBUTED BY column 'c1'
+SELECT distinct col2 c1, col2 c2 into qp_misc_jiras.ctas_dup_dk_1 from qp_misc_jiras.ctas_dup_dk_src;
+ERROR:  duplicate DISTRIBUTED BY column 'c1'
 -- start_ignore
 drop schema qp_misc_jiras cascade;
 NOTICE:  drop cascades to table qp_misc_jiras._tbl10050_test
diff --git a/src/test/regress/expected/qp_misc_jiras_optimizer.out b/src/test/regress/expected/qp_misc_jiras_optimizer.out
index e1c6b95f668030add2e64993db832ba9bd425d3e..3474231d1913da031a716398108261b423c650f1 100644
--- a/src/test/regress/expected/qp_misc_jiras_optimizer.out
+++ b/src/test/regress/expected/qp_misc_jiras_optimizer.out
@@ -4624,6 +4624,10 @@ select test();
  
 (1 row)
 
+-- Test duplicate distribute keys
+CREATE TABLE qp_misc_jiras.ctas_dup_dk_src (col1 int, col2 int);
+CREATE TABLE qp_misc_jiras.ctas_dup_dk as SELECT distinct col2 as c1, col2 as c2 from qp_misc_jiras.ctas_dup_dk_src;
+SELECT distinct col2 c1, col2 c2 into qp_misc_jiras.ctas_dup_dk_1 from qp_misc_jiras.ctas_dup_dk_src;
 -- start_ignore
 drop schema qp_misc_jiras cascade;
 NOTICE:  drop cascades to table qp_misc_jiras._tbl10050_test
diff --git a/src/test/regress/sql/qp_misc_jiras.sql b/src/test/regress/sql/qp_misc_jiras.sql
index e75258c137da90ed0e6e05ea31da175cf4af6682..77ec774fd5e5234d5f0ed53014d98c24b2d22a13 100644
--- a/src/test/regress/sql/qp_misc_jiras.sql
+++ b/src/test/regress/sql/qp_misc_jiras.sql
@@ -2590,6 +2590,12 @@ select test();
 select test();
 select test();
 select test();
+
+-- Test duplicate distribute keys
+CREATE TABLE qp_misc_jiras.ctas_dup_dk_src (col1 int, col2 int);
+CREATE TABLE qp_misc_jiras.ctas_dup_dk as SELECT distinct col2 as c1, col2 as c2 from qp_misc_jiras.ctas_dup_dk_src;
+SELECT distinct col2 c1, col2 c2 into qp_misc_jiras.ctas_dup_dk_1 from qp_misc_jiras.ctas_dup_dk_src;
+
 -- start_ignore
 drop schema qp_misc_jiras cascade;
 -- end_ignore