Possible Regression with OneToOne relation

/**
 * @ORM\Entity
 */
class Top
{
    /**
     * @ORM\Id
     * @ORM\Column(type="integer")
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    protected $id;
    /**
     * @ORM\OneToOne(targetEntity="LevelOne", orphanRemoval="true", cascade={"persist", "remove"})
     */
    protected $levelOne;
    
    public function getId()
    {
        return $this->id;
    }

    public function setLevelOne(LevelOne $levelOne)
    {
        $this->levelOne = $levelOne;
    }

    public function getLevelOne()
    {
        return $this->levelOne;
    }
}

/**
 * @ORM\Entity
 */
class LevelOne
{
    /**
     * @ORM\Id
     * @ORM\Column(type="integer")
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    protected $id;
    /**
     * @ORM\OneToOne(targetEntity="LevelTwo", orphanRemoval="true", cascade={"persist", "remove"})
     */
    protected $levelTwo;

    public function getId()
    {
        return $this->id;
    }
    
    public function setId($id)
    {
        $this->id = $id;
    }

    public function setLevelTwo(LevelTwo $levelTwo)
    {
        $this->levelTwo = $levelTwo;
    }

    public function getLevelTwo()
    {
        return $this->levelTwo;
    }
}

/**
 * @ORM\Entity
 */
class LevelTwo
{
    /**
     * @ORM\Id
     * @ORM\Column(type="integer")
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    protected $id;
    
    public function getId()
    {
        return $this->id;
    }
    
    public function setId($id)
    {
        $this->id = $id;
    }
}

$top = new Top();
        $top->setLevelOne(new LevelOne());
        $top->getLevelOne()->setLevelTwo(new LevelTwo());
        
        $this->em->persist($top);
        $this->em->flush();
        
        $newTop = new Top();
        $newTop->setLevelOne(clone $top->getLevelOne());
        $newTop->getLevelOne()->setId(null);
        $newTop->getLevelOne()->getLevelTwo()->setId(null);
        
        var_dump($newTop->getLevelOne()->getId());
        var_dump($newTop->getLevelOne()->getLevelTwo()->getId());
        
        $this->em->persist($newTop);
        $this->em->flush();