Yep, with guppies you can end up with wall-to-wall fry in no time. Remember the guppy girls can have 4 batches of fry from one wingding with a male, so remove any males months in advance of "okay that's enough guppies". Of course you can always add tetras...they LOVE guppy fry....auto population control.

(well not in a 10 gallon, that's too much)
One can overstock a tank, it's just harder to keep it balanced and keep all the fish healthy. Just about any heated, or under a lamp, 1 gallon tub with some plants(live or silk) and abit of bottom gravel is great for holding fry in to grow some up in peace. Just remember to feed them several times a day, very finely ground up flake food or liquid fry food(best of luck keeping the females from hogging it all away from the babies)....mind you my fry are up for ANYthing and I've seen right tiny tiddlers go and grab a tubifex worm and take off with it...it's longer than they are, but they've got that guppy attitude, "It's MINE, all MINE."
Oops, I forgot to add, give the female guppies a break from bearing fry all the time. Continual giving birth really wears them out and they die much sooner. Find a small tank or container for the couple of males and let 'em have some time on their own, it's good self discipline for them anyways! B)