Description:
------------
Basically i get "aaa" and "bbb" automatically updated also in the content object of the first $p


If i clone the var on return i can solve this, but i didn't understood why

Test script:
---------------
abstract class Tag {
    protected $content = [];

    private function parse ($var) {
        return ($var instanceof Tag) ? $var : (string)$var;
    }

    public function add_content() {
       $this->content[] = array_map([$this,'parse'],func_get_args());
    }
}

class p extends Tag { }

$p = new p;
$p2 = new p;

$p->add_content($p2);
$p2->add_content("aaa", "bbb");

print_r($p);

Expected result:
----------------
p Object ( [content:protected] => Array ( [0] => Array ( [0] => p Object ( [content:protected] => Array ( ) ) ) ) )

Actual result:
--------------
p Object ( [content:protected] => Array ( [0] => Array ( [0] => p Object ( [content:protected] => Array ( [0] => Array ( [0] => aaa [1] => bbb ) ) ) ) ) )