Description:
------------
Overloading results in unexpectable behaviour when using two arrays in overloaded object.

Reproduce code:
---------------
// basic overloading usage

class Test {
    private 
        $vars = array(),
        $vars2 = array();
        
    function __get($name)
    {
       return $this->vars[$name]; 
    }

    
    function __set($name, $value)
    {
        $this->vars[$name] = $value;
    }
    
    // initialize new variable
    function add($name, $value)
    {        
        $this->vars[$name] = $value;

        // this second array is not used anymore - but it causes error
        $this->vars2[$name] = $value;
    }
}    


$obj = new Test();   
$obj->add('order', array(0, 1, 2));

// first test
$obj->order[2] = $obj->order[1]; 
print_r($obj); 

// second test
$obj->order[0] = 99;
print_r($obj); 

Expected result:
----------------
// first test
Test Object
(
    [vars:private] => Array
        (
            [order] => Array
                (
                    [0] => 0
                    [1] => 1
                    [2] => 1
                )

        )

    [vars2:private] => Array
        (
            [order] => Array
                (
                    [0] => 0
                    [1] => 1
                    [2] => 2
                )

)

// second test
Test Object
(
    [vars:private] => Array
        (
            [order] => Array
                (
                    [0] => 99
                    [1] => 1
                    [2] => 1
                )

        )

    [vars2:private] => Array
        (
            [order] => Array
                (
                    [0] => 0
                    [1] => 1
                    [2] => 2
                )

)



Actual result:
--------------
// first test
Test Object
(
    [vars:private] => Array
        (
            [order] => Array
                (
                    [0] => 0
                    [1] => 1
                    [2] => 2
                )

        )

    [vars2:private] => Array
        (
            [order] => Array
                (
                    [0] => 0
                    [1] => 1
                    [2] => 2
                )

        )

)

// second test
Test Object
(
    [vars:private] => Array
        (
            [order] => Array
                (
                    [0] => 99
                    [1] => 1
                    [2] => 2
                )

        )

    [vars2:private] => Array
        (
            [order] => Array
                (
                    [0] => 99
                    [1] => 1
                    [2] => 2
                )

        )

)