MetaData Storage is not consistent

Phalcon 2.0.6, Phalcon\Mvc\Model\MetaData\Files Storage is normal，

return array (
  0 => 
  array (
    0 => 'phone',
    1 => 'uid',
  ),
  1 => 
  array (
  ),
  2 => 
  array (
    0 => 'phone',
    1 => 'uid',
  ),
  3 => 
  array (
    0 => 'uid',
  ),
  4 => 
  array (
    'phone' => 14,
    'uid' => 14,
  ),
  5 => 
  array (
    'phone' => true,
    'uid' => true,
  ),
  8 => false,
  9 => 
  array (
    'phone' => 1,
    'uid' => 1,
  ),
  10 => 
  array (
  ),
  11 => 
  array (
  ),
  12 => 
  array (
    'phone' => NULL,
  ),
  13 => 
  array (
  ),
);

but，Session stroage :

["meta-phoneuid-phone_uid"]=>
    array(4) {
      [0]=>
      array(2) {
        [0]=>
        string(5) "phone"
        [1]=>
        string(3) "uid"
      }
      [1]=>
      array(1) {
        [0]=>
        string(5) "phone"
      }
      [2]=>
      array(1) {
        [0]=>
        string(3) "uid"
      }
      [4]=>
      array(2) {
        ["uid"]=>
        int(0)
        ["phone"]=>
        int(0)
      }
    }