Thread: double insert in db

Hi,
I have problem with inserting data in database. My code:
controller

Code:

if ($form->isValid($request->getPost())) {
                        $values = $form->getValues();
                        $analize = array();

                        foreach($values as $key => $value) {
                            if(0 != $value) {
                                $analize[substr($key, 1)] = $value;
                            }
                        }
                        $mapper->save($analize);
                    }

mapper

Code:

public function save($analize)
    {
        $uid = substr($_COOKIE['uid'], 32);
        $results = Zend_Json::encode($analize);
        $sql = "INSERT INTO  `tbl_values` (`user_id`, `result`) VALUES ({$uid}, '{$results}');";
        $stmt = $this->_db->query($sql);
        $results = $stmt->execute();
    }

when I write form results to db I get two identical rows. Anyone know why?
thnks