That's the first time I've ever seen that. I've grown Frogspawn, Hammer, and Torch coral all growing into each other for years.
Of course I've heard (just recently) of a similar incident where coral that "seem" the same but from a very different region engaged in warfare in a smallish tank.
Wicked cool pic Doogle. You'll need to put a LOT more distance between them because this probably isn't a short term solution (but could make for some more amazing pictures).