Multi-boxing/multi-plexing is a bit more cheaty than the above example. Running multiple machines wouldn't necessarily allow you to play all those characters simultaneously, thus wouldn't necessarily be illegal.
Multi-boxing, as far as UO is concerned, does rely on being able to multi-client. The perpetrators open multiple CC clients on the same machine (usually 3-5) and log in on virtually identical characters on each account, they then use third party software to replicate keystrokes and mouse movements across all those clients. This allows all those characters to act as one, xheal via scripts, and generally bend the EM drop mechanic over a barrel and have their way.
When you see a bunch of near-identical characters stacked on top of eachother moving as one unit, they are a multi-boxer. The favorite type seems to be wraith throwers, though I've also seen sampires.
Mesanna likes to hide behind the falsehood that the GMs can only action the account of someone who is AFK macroing in regards to this problem, even though the RoC/ToS blatantly state otherwise. I can only see tinfoil hat reasons for her to continue to allow such activuties.
