Quoted from Atomicboy:I'm betting it's mono, as you would have clear missing sections if not, like when you have a problem with one speaker for a stereo, it becomes very evident.
Having said that, even a mono stereo will sound 10 times better with a second speaker spread out. I have never heard a bad thing about someone going this route and it not making a difference.
I've had my Nintendo Entertainment System modded to do faux stereo sound, even though it was only designed to be mono. It has something to do with intersecting signal paths before they're all mixed into a single Mono output - so certain sounds would come out of the left or right speaker after the mod, though it's not like any of the sounds were programmed specifically with a direction in mind. Not sure if I'm explaining this properly, but it wouldn't be beyond my imagination if someone did something similar for one of these games.