in Siege it's intended. Otherwise people would just equip the worst piece of equipment once the match is about to end.
In battle, however, it should get reset everytime your multiplicator increases/decreases. I also checked the code again, it looks ok, and i cant understand how this can happen.
If anyone can remember - how did the round end? like, normall, or a draw, MotF, map change, etc etc. Need more info to fix it.
(About the looting problem: Cant fix that one for now. If you pick up an item you dont posess, and spawn with it, and it breaks, that will be deducted from your money ingame, but not from the website money)