In a 20g long (30in) with LOTS of landscaping, and some kind of mid-tank divider (aline of rock or a big piece of driftwood) you could probably do it. They would either work things out and divide up the tank, or one would dominate and make the other male's life miserable (at which point you would need to remove him). It's always a toss up with cichlids. Each fish is very much an invididual. The key to getting multiple dwarfs to coexist in a small space is to raise them up together from a small size (smaller than is normally available in LFS). Good Luck
PS both male would absolutely have to be introduced simultaneously.