CakePHP Hash :: diff工作不正常

I want to send to my view 2 arrays - second one shouldn't have elements from the first one. I used Hash::diff but it doesn't work great with CakePHP arrays.

    $edited = $this->Instrument->find('all', array(
         'conditions'=>array(
            'status' => '1'),
        'fields' => array('Instrument.id',[and other fields]),
         'order'=> array('modified'=>'desc'),
         'limit'=>100
     ));


    $new = $this->Instrument->find('all', array(
         'conditions'=>array(
            'status' => '1'),
        'fields' => array('Instrument.id', [and other fields]),
         'order'=> array('added'=>'desc'),
         'limit'=>5
     ));


 $this->set(array(
     'edytowane'=>Hash::diff($edited, $new),
     'nowe'=>$new
 ));

But after that I sometimes have few the same records in $edytowane as in $new variable. What do I wrong ? :)

I have done it like that - it's rather a bit not efficient, but works fine for me:

$ids_nowych = array();   

$new = $this->Instrument->find('all', array(
         'conditions'=>array(
            'status' => '1'),
        'fields' => array('Instrument.id',[and other fields]),
         'order'=> array('added'=>'desc'),
         'limit'=>5
     ));


foreach ($new as $n){
        $ids_nowych[] = $n['Instrument']['id']; 
}


    $edited = $this->Instrument->find('all', array(
         'conditions'=>array(
            'status' => '1',
            'NOT' => array(
                'Instrument.id' => $ids_nowych
            )),
        'fields' => array('Instrument.id',[and other fields]),
         'order'=> array('modified'=>'desc'),
         'limit'=>100
     ));




 $this->set(array(
     'edytowane'=>$edited,
     'nowe'=>$new
 ));