I typically carry two, a Beretta PX4 Compact 9mm loaded with 147gr HST in a Kramer IWB#3 horsehide holster and a S&W 642-1 loaded with 135gr SB-GDHP in a Wilderness Tactical Renegade ankle holster.
As to whether two or more are too much, that'll depend on your personal situation. For me, I went with my set-up because I wanted to be able to access a gun while seated, particularly in a car. AIWB or crossdraw would be good options, but neither work for me. Strongside IWB could work, but may require some contortions to get to the gun. I don't want to leave a gun in the car if I can avoid it and I'd rather not deal with unholstering/reholstering in the car. Ankle carry gives me a more accessible gun while seated in the car. But it's not very accessible at other times, and obviously doesn't allow for drawing while moving, so I ankle carry in addition to IWB. Plus, guns, being mechanical devices, have the potential to fail at any time, even if they run reliably and haven't failed before. The odds of both guns failing at the same time would be pretty low, I think.
So, I think it's a good idea to consider. For example, if you wear heavy clothing during the winter, it may make sense to keep a snubby BUG in a jacket pocket for easier accessibility if you carry a sidearm under your jacket.
But I certainly don't think it's a necessity. It may be too much work for some people. For me, it's no problem carrying 2 guns with my set-up. Of course, there are times when I only have my 642 in an IWB holster, and times when I don't have a gun on me at all.
