These double map pouches will technically fit 2 G3 mags in each side, but with all the ridges and pokey bits they don't slide past each other well enough to be practical for more than 1 in each side. But with 1 mag in each side they work great.
CETME mags for all practical purposes only fit 1 on each side, and even then their curve causes them to bind up in the straight pouches making mag extraction somewhat difficult. ("for all practical purposes" I mean can you shove 2 in? Yes, if you try hard enough. Can you get them back out again? Eventually.)
7.62x39mm 30 round AK magazines fit 2 but are too long, although 20 rounders would fit and close. AR-15 30 round magazines fit in twos perfectly fine.
I won't take off stars for any of this though, they weren't designed with either of these guns in mind. They are what they are However, I did want you guys who have these to know how well the pouches work for them.