I don't know about that, but if you mean at the same time, then yeah you can't. It's like two people logging into the same MMO account. Though I'm still not completely certain what the problem is, sorry that I'm not much help. I do know that I switched from my Laptop over to my Desktop before for using Diorama Studio and Battle Rondo, so I don't think that could be a problem, but who knows. Sorry again.