add_filter('wf_shipping_skip_product','skip_my_products',10,3);

function skip_my_products($skip = false, $product, $package){
	$shipping_class_goup = array('class-a','class-b'); // if these shipping classes coming together in the cart
	$shipping_class_skip = 'class-a'; // If multiple shipping class of above in the cart, skip this product.

	$shipping_class = array();
	foreach ($package as $key => $item) {
		$shipping_class[] = $item['data']->get_shipping_class();
	}

	if( $product['data']->get_shipping_class()==$shipping_class_skip && ( count( array_intersect( $shipping_class, $shipping_class_goup ) > 1 ) ) ){
		return true;
	}
	return false;
}