class redeclare error help please !!!

[eluser]Unknown[/eluser]
Fatal error: Cannot redeclare class Photo in C:\wam\www\system\application\models\photo_models.php on line 15

Code:

class Photo extends model
    {
       function photo()
        {
            parent::Model();
        }
        function Get_photo($cat)
        {
            $query=$this->db->get_where("photo",array('cats' => $cat));

            return$query->result();
        }
    }

please can someone help