GBATemp
As you can see, this is the sign-up page for this website. Scroll down to the bottom to see what the last thing is that the new user must do before he/she is able to sign-up. Now is there any way Jon could do this on CB sign-up? "I agree not to make another account or share the one I make here."
This way you could just outright ban each multi, as they themselves had to type out this rule in CB land before playing. I think this would make a bigger impact than just a checkbox.
