In which scenario system applies payable payment discount of all item lines and why.

we have created a payable invoice through PO, then created a payment and also applied discount on the payment with 4.5 percent to the total amount, when we performed mass addition system shows one extra transaction with all items as (Discount) with 4.5% of item value for asset capitalization. we believe system working fine the strange think is previously we allied discount on 2 invoice but system behavior for not as above, so please can any one explain and guide what we did wrong now so the system applied discount on all capitalization entries and not in previous ones

Regards

Qaiser Hassan Awan