PHP Shopping Cart สอบถามเรื่อง SESSION 2 ชุด เช่น เช่าชุด/สั่งซื้อ มีปัญหา

<?
ob_start();
session_start();
	
if(!isset($_SESSION["intLine"]))
{

	 $_SESSION["intLine"] = 0;
	 $_SESSION["strdressID"][0] = $_GET["dressID"];
	 $_SESSION["strQty"][0] = 1;

	 header("location:order_show.php");
}
else
{
	
	$key = array_search($_GET["dressID"], $_SESSION["strdressID"]);
	if((string)$key != "")
	{
		 $_SESSION["strQty"][$key] = $_SESSION["strQty"][$key] + 1;
	}
	else
	{
		
		 $_SESSION["intLine"] = $_SESSION["intLine"] + 1;
		 $intNewLine = $_SESSION["intLine"];
		 $_SESSION["strdressID"][$intNewLine] = $_GET["dressID"];
		 $_SESSION["strQty"][$intNewLine] = 1;
	}
	
	 header("location:order_show.php");

}
?>

<?
ob_start();
session_start();
	
if(!isset($_SESSION["intLine1"]))
{

	 $_SESSION["intLine1"] = 0;
	 $_SESSION["strReserveID"][0] = $_GET["ReserveID"];
	 $_SESSION["strQty1"][0] = 1;

	 header("location:order_show.php");
}
else
{
	
	$key = array_search($_GET["ReserveID"], $_SESSION["strReserveID"]);
	if((string)$key != "")
	{
		 $_SESSION["strQty1"][$key] = $_SESSION["strQty1"][$key] + 1;
	}
	else
	{
		
		 $_SESSION["intLine1"] = $_SESSION["intLine1"] + 1;
		 $intNewLine1 = $_SESSION["intLine1"];
		 $_SESSION["strReserveID"][$intNewLine1] = $_GET["ReserveID"];
		 $_SESSION["strQty1"][$intNewLine1] = 1;
	}
	
	 header("location:reserve_show.php");

}
?>