I have a 29g with easily over 200 polyps of discosoma (green stripe, red, superman and purple with blue spots) that all get along fine. They do not however get along with the floridas (have never gotten my yumas close enough to find out), protopalys (protopalys lose the battle) or kenya trees (discos are shriveled and discolored where contacting the base of the kenyas, but they still grow). My branching frogspawn seems to be bothered by them as well, but there is also a shading issue so I'm not sure which is really the problem).
You could always try placing them close together on a temporary basis and see what happens. Ive heard of corals that peacefully coexist in one tank, but go to war in another. I doubt they are going to kill each other off in one day so might be worth checking it out.