diff --git a/core/lib/Drupal/Core/Entity/Entity.php b/core/lib/Drupal/Core/Entity/Entity.php
index e76a7d0..ecf837b 100644
--- a/core/lib/Drupal/Core/Entity/Entity.php
+++ b/core/lib/Drupal/Core/Entity/Entity.php
@@ -314,6 +314,7 @@ public function createDuplicate() {
     $duplicate = clone $this;
     $entity_type = $this->getEntityType();
     $duplicate->{$entity_type->getKey('id')} = NULL;
+    $duplicate->enforceIsNew();
 
     // Check if the entity type supports UUIDs and generate a new one if so.
     if ($entity_type->hasKey('uuid')) {
diff --git a/core/tests/Drupal/Tests/Core/Config/Entity/ConfigEntityBaseUnitTest.php b/core/tests/Drupal/Tests/Core/Config/Entity/ConfigEntityBaseUnitTest.php
index 9deeaa6..0a37f4f 100644
--- a/core/tests/Drupal/Tests/Core/Config/Entity/ConfigEntityBaseUnitTest.php
+++ b/core/tests/Drupal/Tests/Core/Config/Entity/ConfigEntityBaseUnitTest.php
@@ -369,6 +369,8 @@ public function testCreateDuplicate() {
     $duplicate = $this->entity->createDuplicate();
     $this->assertInstanceOf('\Drupal\Core\Entity\Entity', $duplicate);
     $this->assertNotSame($this->entity, $duplicate);
+    $this->assertFalse($this->entity->isNew());
+    $this->assertTrue($duplicate->isNew());
     $this->assertNull($duplicate->id());
     $this->assertNull($duplicate->getOriginalId());
     $this->assertNotEquals($this->entity->uuid(), $duplicate->uuid());