Fixed #16247

framework/base/Component.php

@@ -307,8 +307,15 @@ public function __call($name, $params)
     public function __clone()
     {
         $this->_events = [];
-        $this->_eventWildcards = [];
-        $this->_behaviors = null;
+        $this-> _eventWildcards = [];
+
+        if ($this->_behaviors !== null) {
+            $behaviors = $this->_behaviors;
+            $this->_behaviors = null;
+            foreach ($behaviors as $name => $behavior) {
+                $this->attachBehavior($name, clone $behavior);
+            }
+        }
     }
 
     /**

tests/framework/behaviors/CloningBehaviorTest.php

@@ -0,0 +1,57 @@
+<?php
+/**
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright (c) 2008 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+namespace yiiunit\framework\behaviors;
+
+use yii\base\Behavior;
+use yii\base\Model;
+use yiiunit\TestCase;
+
+/**
+ * Unit test for cloning behaviors when objects are cloned.
+ *
+ * @group behaviors
+ */
+class CloningBehaviorTest extends TestCase
+{
+    public function testCloningObjectsClonesBehaviors()
+    {
+        $model1 = new ModelWithBehavior();
+        $model1->myBehaviorProperty = 'foo';
+        $model2 = clone $model1;
+
+        $this->assertEquals($model1->myBehaviorProperty, $model2->myBehaviorProperty);
+    }
+}
+
+/**
+ * Test Model class with a behavior attached.
+ *
+ * @mixin BehaviorWithProperty
+ */
+class ModelWithBehavior extends Model
+{
+    /**
+     * {@inheritdoc}
+     */
+    public function behaviors()
+    {
+        return [
+            'myBehavior' => BehaviorWithProperty::class
+        ];
+    }
+}
+
+/**
+ * Test Behavior class with property.
+ *
+ */
+class BehaviorWithProperty extends Behavior
+{
+    public $myBehaviorProperty;
+}
+