Space and efficiency...I have tried thinking of all the ways I could make my tadpole and froglet rearing easier, but some things can't be changed too much. I used to raise Tarantulas and Scorpions so I can relate to your questions. It's quite a daunting task to find your tarantula's egg sac broken open and there's 400-600 spiderlings that need to be housed and fed individually in deli cups.

This last summer I was dealing with close to fifty Leuc froglets and all I could come up with was using Rubbermaid/Sterilite tubs that I set up like a vivarium. I could see in and they were relatively portable.

Mixing the two froglets for a short period of time? I've never read of anyone doing it and I've read quite a bit about froglet care. Maybe they would get along, maybe not. I myself would not do it for the reasons mentioned above.