However, If you are taking about playing a normal 2 player shooting game on two different screens, that should be completely possible.
The Aimtrak guns work like a mouse, so if you had two guns and two IR strips (one for each TV) and then mirrored or split the normal MAME output to both of the TVs, it would let each gun user have their own screen and gun, and both would play the same game at the same time, and see the same output, just more elbow room I guess.
Their is no reason I can think of that the above described setup shouldn't work.