Temperature of developer and very fresh developer could be a problem for paper negs. If temp was right but it was fresh developer, that could work too fast too. If you have three film holder, take a light reading, expose it at that, on the second shot, make it the same exposure, on the next set, cut the exposure in half, do that again, and again. Keep notes as to which one film holder has which exposures in it. Develop one at the correct time/temp; change developing time based on that. It's worth a shot - and paper isn't as expensive as film.