It's theoretically possible to get decent efficiency in a springer war by "dual" wielding spring pistols....in theory, you could buy yourself up to ten spring pistols, four leg holsters, four belt holsters, and a shoulder holster rigged for two pistols. If you were really devoted to it, you could technically learn to fire two shots off with each spring pistol, reholster it, and unholster the next pair of pistols. The flip side would be the dramatic loss of mobility and stealth...plus the massive delay in cocking time. The more I think about it, it seems like you would only have one good cycle of draw-shoot-holster-draw again before you got rushed or ended up emptying the mag in each pistol without getting chance to repeat the cycle.
Although GBB dual wielding may not be as easy as it first appears, I do not know dual-wielding is totally out. If you don't mind the extra weight, I can see how a compact secondary sidearm could be useful. I don't know that it would prevent getting shot in those hypothetical situations, but the moment you got a kill with the secondary sidearm you'd have a tremendous sense of accomplishment.
DRK, if you get the chance to dual wield LMGs, do try to get a video!