OK, from my years of keeping RBTAs:
They move. Yes, once they find a spot they like, they will stay put. FOR A WHILE. Then, they take a trip around the tank or two.
Once they split, which mine do quite often, they seem to wander a bit, and then one or both end up back where they started. You HAVE to KEEP the tank anemone-proofed. At ALL times.
They will kill off anything around them. That's just their nature. If you keep one, make sure that everything in your tank can be moved.
As noted earlier, try to find someone's clone. I have them occasionally, but when I do they are usually put up for adoption in the exchange program. Of they 20-30 or so clones I've had, I've never lost one that wasn't my fault: One in a powerhead, one by trying to get it off a rock and it got too cold. Mine are EXTREMELY hardy, and there are many, many clones of mine running around on MAAST.
Bill
215g FOWLR... and anemones, GSP, gorgonians... carp, that isn't FO!
"I killed my first SW Fish in 1971..."