Incorrect batch in BAPI_OUTB_DELIVERY_CREATE_STO

I am creating outbound delivery using BAPI_OUTB_DELIVERY_CREATE_STO. Batches picked are different than that picked using VL10B.

The batch picked for 1st line item of delivery is repeated for 2nd line item even though there is not much stock available for that batch to suffice the 2nd line item

When I create the delivery using VL10B, then the batch is only picked for the 1st line item of delivery.

Please help.