Oh wow. Different emails I guess I can understand but using an IP scrambler just seems really over the top for just an RP >_>
Apart from just noticing things in the writing style, there's other things like AIM. Do they sign on/off at the same time. Try to talk to both at the same time and see if you get simultaneous or consecutive responses. Also I was recently in an RP that occasionally had Teamspeak Weekends, which is like Skype. You can't be two people on Skype unless they happen to own a Darth Vader voice scrambler.