Looks like multiboxing is becoming more and more common lately. I would like to present to the community some screenshots about a particular multiboxer, so the GMs can act accordingly:
Sure, these screenshots do not prove anything, simply because the toons might be "on follow" to the specific player's avatar.
This particular screenshot is ample proof that not only the specific player in question is multiboxing, but also uses a third-party program to execute skills across all clients.
Taken directly from Turbine's Code of Conduct about LotrO:
18. You may not create, post, use or distribute any utilities, emulators or other third party software tools without the express written permission of Turbine (including, without limitation, macroing programs, botting programs, server emulators, client hacks, map hacks, and data gathering utilities).