Hi! Sorry for the late response. I'm a full-time student in a non-CS field, so staying on top of programming stuff is difficult.
My recollection of the game was that picking up previously collected credits did not award you the credits again. That being said, I could very well be wrong, and regardless I do think it's better from a design perspective to allow farming credits.
I should have some time in the next couple of weeks to remove the system I put in to disable farming. Will comment again then!