I have had success with housing my two males together. I had to do it once while I was between houses (escrow closed on the house I was selling two weeks before escrow closed on the house I was buying!) and had to crash at a friend's house. They survived. I had them apart for a while, then together for a few months, then apart again when I had a big enough cage for the smaller one.
THEN came the San Diego wildfires last October/November. I piled both boys into one cage and got the H-E-Double-L out. Once we were let back in, I didn't have the energy to re-do the setup (I had mis-placed one of the lids in my rush to evac). So.... the boys got put into the big tank together. They've been doing fine ever since, eating nicely and behaving.
The important thing is HUSBANDRY. I have to be extra vigilant about keeping after the cage to make sure that there's no poopy about. I also make sure to feed them separately - I have heard too many horror stories about two snakes trying to eat the same mouse and having one eat the other!
One thing I wish I hadn't done in the wildfires is house all my rats together. I had 1 male and 4 females and was only planning on one pregnancy for the next couple of months. A few weeks later, guess what I had? A GOZILLION little baby rats! Note to self: When evacuating, KEEP SEXES SEPARATE!