Basically, there are only three mags sizes: those for a 1911-type mag, those for 9mm/.40 mags, and those for the larger Glock .45 mags. (I'm sure there are other mags, but those are the most common.)
I've got a Fobus double that I use for everything -- (Its for th S&W 6906, I believe). It handles 1911 mags, CZ, mags, Glock 9mm and .40 mags, and mags for every gun I've got, including the full-size .45 mags by Mec-Gar (for EAA and CZs.)