Multicoupon plugin and serial assignation

-- HikaShop version -- : 5.1.5
-- HikaSerial version -- : 5.0.0
-- Joomla version -- : 3.10.12
-- PHP version -- : 7.4.33
-- Browser(s) name and version -- : Firefox 136.0.2

Hello,

I use HikaSerial to generate coupons which can be use once. When user adds to card product, enters first coupon code it reduces price in cart total. Then user enters second coupon code and it also reduces price in cart total. Both coupon codes are displayed in cart. Then user finishes order. That works well. But in HikaSerial->Serials list i see only one code attached to order number and this code was NOT used for reducing price. It is totally random picked coupon code and displayed in Hikashop Order also (Serials part). In "Additional information" part of Hikashop order window i can see both of used coupons and it displays correctly. Where this third coupon comes from and its assigned to Order? It also shows same info on emails.

The serial that is automatically assigned to Order is still shows as available in HikaShop->Orders->Coupons. It still shows "1 (1 left)". But if i try to use it in next order, message appears: "You used the serial "FK25-TQXSR".
Btw, i also can't find this message in language file, so it can not be translated