ช่วยดูโค็ตให้หน่อย ดัก ค่าซ้ำใน listbox รบกวนดูให้หน่อยครับ

            $arr[3][count($_POST['seatID'])];
							                                                         

for($i=0;$i<count($_POST['seatID']);$i++)
{
                for($j=0;$j<sizeof($arr[3][count($_POST['seatID'])]);$j++)
                {
                        if($arr[0][$j]==$_POST['carID'][$j]&&$arr[1][$j]==$_POST['departureDate'][$j]&&$arr[2][$j]==$_POST['seatID'][$j])
                                {
                                                $dup = 1;
                                                
                                }
                }
                
                if($dup<>1)
                {
                                $arr[0][$i] = $_POST['fleetID'][$i];
                                $arr[1][$i] = $_POST['departureDate'][$i];
                                $arr[2][$i] = $_POST['seatID'][$i];
                }else
                                {
                                                echo "<script>alert('data dupplicate!!');</script>
                                                      <script>window.location='edit_seat.php';</script>";
                                }
                
                //$dup = 0;
                
}