Kthanid:
No, that's not at all true, at least it's not anymore true than saying "anyone who buys it from GOG get's infinite copies to give to whoever they choose".
What you are buying is a single license to the game, what you are being given is several avenues to install that game.
Patchumz:
The Humble Bundle (most popular indie game bundle) usually gives at least Steam and standalone, if not Desura and other services too, this is no different.
true. you are both right. i didn't think about these examples.

Wu Tse