$arr=array(
                        array('name' => 'aa','id' => '456'),

                        array('name' => 'bb','id' => '25',),

                        array('name' => 'cc','id' => '25',),

                        array('name' => 'dd','id' => '456',),
                    );

                                $newArr=array();
                                foreach($deals_info as $key=>$value){
                                    if(!isset($newArr[$value['id']])){
                                           $newArr[$value['id']][]=$value['name'];
                                    }else{
                                        foreach($newArr as $k=>$v){
                                            if($k==$value['id'] and !in_array($value['name'],$newArr[$k])){
                                                    $newArr[$k][]=$value['name'];
                                            }
                                        }
                                    }
                                }