I assume you are loading to an infoobject that is a concatenated or compounded verson of BELNR & HKONT? If so:
- if you want to check in older loads, you need to do a select on the corresponding target table (the P or Q table in case of infoobjects, the A-table in case of DSO) to see if the entry already exists
- If you want to check in the current load you first have to make sure you have semantic partitioning on BELNR is active in the DTP in order to assure you have all lines for a certain BELNR nr in 1 data package. Then in you coding apply a similar logic where you keep track of combinations already processed so you can verify every record against that check table and decide wether to keep it in your datapackage or ignore it