Inventory entity with 2 (or more) same service / product included, mistake taxes

If I include 2 (or more) times same product (or same service) into an inventory entity, when I edit, items take, always, first one taxes values. This because

function getInventoryProductTaxValue($id, $productid, $taxname) {...}

into include/utils/InventoryUtils.php: it gets tax value by entity id and product id. It should get by lineitem_id