you mean spread out on the other side of the stage or something?1 amp over here, 1 amp over there.
not so great, you get low end loss between them, because lots of the bass waves just happen to be the distance between the two rigs, and get cancelled.
your ballsiest sound will be from the rigs right together, reinforcing each other's low end.
also, no need for any splitters or "stereo" or whatever; the effects send from one amp can go to the effects return of the other, at which the first amp becomes the preamp for both rigs.