That would be reverse banking I think
Scrapbanking is when you give scrap for spare weapons
Scrap banking is you give any 2 weps for 1 scrap
Reverse banking is you give 1 scrap for any 2 weps
Selling is you give 1 scrap for one specific weapon
Edit: when I said "you", I mean the person that is not doing the specific action (the person not scrapbanking is the one giving the weapons)