It probably is allowed. You'll need a hefty computer to do so, though. If on Windows: Launch normal Windows client Launch Sandboxie client Launch vmware client (can use sandboxie in vmware to have 4 clients too) If on Mac: Launch normal Mac client Launch Parallels client Launch Sandboxie client on Parallels
http://royals.ms/forum/threads/how-to-multiclient-on-windows-8-8-x.13963/ This would work for any version of windows, I multiclient 2 clients so I just open up 2 virtual machines, but I could also open a mapleroyals client on my original computer. Also depending on your RAM its possible to open more machines.