guess i should have worded it a bit differently..
i meant games that drive 2 screens independently off a single board.. rather then 2 screens being ran by separate boards but linked or a game that just required more then one screen for a single instances of game play.
like cyber ball and outrunners.. they can play screen vs screen but they can also play 2 games independently.. apparently off a single board it's as if you have two copies of the game running in mame at the same time.
run and gun looks like it might be one.. although some reason there is'nt anyway to access the 2nd screen in mame.
the rest of those are games require 2 screens but are'nt independent (it's still a single game playing)
such as punch out, xmen (6play), and ninja warriors.