Php Array Splice does not compare size

The array should push new item in array instead of increasing quantity when size is different, but it increases quantity and overwrites size of the previous item. Has anybody a constructive solution please?

if (isset($_POST['pid'])) {
$pid = $_POST['pid'];
$size = $_POST['size'];
$wasFound = false;
$i = 0;
// If the cart session variable is not set or cart array is empty
if (!isset($_SESSION["cart_array"]) || count($_SESSION["cart_array"]) < 1) { 
    // RUN IF THE CART IS EMPTY OR NOT SET
    $_SESSION["cart_array"] = array(0 => array("item_id" => $pid, "size" => $size, "quantity" => 1));
} else {
    // RUN IF THE CART HAS AT LEAST ONE ITEM IN IT
    foreach ($_SESSION["cart_array"] as $each_item) { 
          $i++;
          while (list($key, $value) = each($each_item)) {
              if ($key == "item_id"&&"size" && $value == $pid&&$size) {
                  // That item is in cart already so let's adjust its quantity using array_splice()
                  array_splice($_SESSION["cart_array"], $i-1, 1, array(array("item_id" => $pid, "size" => $size, "quantity" => $each_item['quantity'] + 1)));
                  $wasFound = true;
              } // close if condition
          } // close while loop
       } // close foreach loop
       if ($wasFound == false) {
           array_push($_SESSION["cart_array"], array("item_id" => $pid,"size" => $size, "quantity" => 1));
       }
}
header("location: cart.php"); 
exit();
}