Buying on G2A with cashback disccount

Hello guys, so ive been buying some games in G2A and ive been using some CODES from streamer to get the 3% cashback. The thing is that i can only use the same code once. But i can find a diferent code and use that to get again the 3% cashback. Does anyone knows where to find that codes? and if it's ok to do this?
Thanks