Theres a way to sort this problem out but many other people wont like it as it would ruin the game, a lock IP address, which means if you log into 2 accs, the 1st acc gets logged out as the 2nd one enters the game...
Now I know of people who use 2 Accs, especially when fixing their gear, Its much faster to log into 2 accs, One with your craftsman and the other warrior/mage which hands the crafter the stuff to fix, instead to having to put items into a chest/bag and logging out and back in.
Now this comes to the next point people will log 30accs and play the IDOCS, Maybe write into the system that only 2 clients can be used at same time from one IP, still by having a fake IP this would be just useless and you can always forge the IP if you are tech savvy.