Who needs an entire second computer and account when there's an app for that?
David I doubt that you're being spectraitored that much. It might happen from time to time but is mumble even up for most team games? Also, if they're doing it in a casual context over beers, then they're probably not gaming you too hard.
I do think it's really bad to spec cheat like that though, just that beer is conducive to poor decision making (in fact that might help your win-rate even if they have the information advantage XD). If they were doing it in a premeditated fashion I'd be calling for their blood (given sufficient evidence).
I would try to develop a style that limits what they can do with an information advantage. If they're serious you will still be fighting up hill, but you'll be much better off than if you're pulling shifty tricks like rushes etc.
