I *think* they're marked differently on the box.
The only Glock (19) case I have in the pile from them is labeled "3 15rd" and came with three magazines. The "non-mil/leo" case is physically separated from the other guns along with the different prices. Never really made sense for me to look that deep into it, I'm active military and they'll sell me a pistol for less money with MORE magazines- so it's a no brainer on which to buy.
Also, that shop is a good outfit- can't imagine that they would remove a magazine from a factory set on their own then pawn it off to people while saying "it's the way Glock does it"