the third guy, who was friends with the twins, he was a part of their settlement and collected a decent share of money as well.
as far as eduardo getting the diluted shares, there's a fair amount of info summarized very quickly or left out of the movie.
basically, yes the other roommate who had 5% of the company did know about what they were doing. eduardo apparently did legit. piss off mark and the third roommate that whole summer by not nly not moving to the bay area with them but also bc he purposefully was lagging on signing off on many important documents that needed his signature so they could move ahead with things. as they said in the movie, things were moving very fast at that time. he was apparently legit. holding things up. so mark got pissed and forced him out. which was f'ed up, and he paid for it. eduardo is stil an idiot though for signing that stuff without a lawyer reviewing it...thats crazy. but then of course it gets to the crux of the movie, as he trusted his friends, as many would in the same scenario.
great movie, so much to discuss and think about. amazing soundtrack too from my favorite artist trent reznor. the mood he set throughout was so cool.