Woocommerce将多个产品添加到购物车不适用于购物车上的第一个产品

Question

I create a function on my woocommerce theme to add multiple product to cart with single button.

    function bulk_add_process() {
        if ( ! is_admin() ) {
            if ( isset( $_GET['bulk_add'] ) && $_GET['bulk_add'] ) {
                $data = $_GET['data'];

                foreach ($data as $id => $qty) {
                    $added = WC()->cart->add_to_cart( $id, $qty);
                }
            }
        } 
    }
    add_action( 'wp_loaded', 'bulk_add_process' );

My function work normally when there is no product on cart.

    Example (I am adding 1 product A and 1 product B):
        Initial => Cart: Empty
        After Add to Cart => Cart: A:1, B:1

The problem is when I add same product for the second time, the amount of first product on cart didnt get updated.

    Example (I am adding 1 product A and 1 product B again):
        Initial => Cart: A:1, B:1
        After Add to Cart => Cart: A:1, B:2
        (Product A's amount didn't increased)

Is there any solution?