have been searching and a couple people mentioned a ps/2 splitter but I don't know if anyone has ever actually used 2 ps/2 mice and made it work.
They only way that I have seen it work is with serial mice and the ps/2 to serial adapters won't work with these.
You can get Ps/2 to USB adapters (I think radio shack carries them) and use Analog Mame. Only problem is it doesn't work under XP.
Microsoft doesn't want people to easily have two or more users using a PC at the same time, which could be done with shareware if XP still supported independent addressing of mice and keyboards. With dual monitor support, USB, and high speed processors it should be easy to split a PC in half for office applications, but MS killed the idea by not supporting the needed calls in XP. Needing another PC means needing another licence for Windows.
It still should be possible in 2K and 9x, but the idea could really catch on if it'd work in XP. It's surprising that I haven't heard of any software that did this yet, though back in Win 95 days they had hardware that let you do this.