Anzhanto (atys)It is possible, the client does not complain at all about one character's interface.icfg replacing another's.
At one time, a very very long time ago, some clever homin wrote a utility that could export the markers from the config file and then load a new set of markers. This, of course, started a spate of map sharing which Nevrax quashed (as if homins wouldn't sit down together and share such things) and the utility vanished. I'm not sure if Nevrax changed the formatting/encoding of the icfg file to prevent this happening again or if it's simply remained taboo since then.
Whether or not the company cares, if of course another matter entirely.