I have never tried it, however, since they are all the same species they should be fine. If you do, just keep any eye on the tissue for signs or stress or damage. If you being to see any then move them apart.
I have several Euphyllia corals (Hammer, Frogspawn and Torch) that are all growing with their polyps in contact with each other and I have not observed any damage. But when they brushed against a Montipora...there were white spots from were stings occurred.