While it would be pretty difficult to multi-box it anyway, The Chronicles of Spellborn's in-game EULA specifically states that you can "own multiple accounts, but only play one at a time." If you log into the client and read the EULA, you can see this for yourself. There is a free trial.

I'm trying to find an online link to the EULA, but haven't been able to so far. Maybe when the game goes live it will be available on their website: http://www.tcos.com

(Note that TCoS is a subscription-based MMO.)