Yeah I was about to say...it's never been an issue because there are other pieces of software that implement an advantage for the end user.
If one player uses 3rd party software to gain an advantage over another player it's generally termed as cheating. Mb skates on that fine line.
Personally I don't understand the real benefit outside of pvm. I'm also pretty sure the designers of AO never intended for a single player to control more than one account in a PvP encounter.