Description:
------------
After tens of hours I have isolated an issue where setting one property sets the same property of the same class of different instance (verified by objects hashes).

I finally managed to fix the issue by the following code:

    public function __clone()
    {
        $elems = $this->elements;
        unset($this->elements);
        $this->elements = $elems;
        ...
}

I was not able to isolate this issue to short test code. Please confirm, that the following code is normally never needed if the "elements" property is an array and please check the source of PHP briefly for this issue. I have full access to the server so I can test anything.