Right now I wouldn't even worry about trying to run 2 clients on one machine I had 4 copies of FFXIV on pre-order and cancel .the beta-client is a resource HOG and the specs to run it are High.The benefits of dual boxing this game is seriously lacking they made this game to cater to the causal player. which isn't bad but I'm not hearing good things about it so far other then they need to wait finish the game properly

and to put it bluntly I don't think anyone has tried to run 2 clients yet on one machine for the beta .