Identify yourself!

<?
$a = array(1,2,3);
$b = array(1,2,3);

var_dump($a === $b); // true;

$a[] = 4;

var_dump($a === $b); // false

Result:

bool(true)
bool(false)

In other words: You can't check if you have two variables that point to an array are in fact pointing to different arrays or if they are pointing to the same array.