Strange PHP Behaviour

$a =& new Book('test1');
$b = $a;
debug_zval_dump($b);

$c =& new Book('test2');
$d = &$c;
debug_zval_dump($d);

/*
Output:

Deprecated: Assigning the return value of new by reference is deprecated in /var/www/y/y.php on line 35


Deprecated: Assigning the return value of new by reference is deprecated in /var/www/y/y.php on line 39

object(Book)#1 (1) refcount(2){   <--- !!!
  ["title":protected]=>
  string(5) "test1" refcount(1)
}
object(Book)#1 (1) refcount(1){   <--- !!!
  ["title":protected]=>
  string(5) "test1" refcount(1)
}