Of course
Yes. So does CoD2 / CoD4 / Spore / Sims 3
You can interchange and swap the given CD-Keys of the whole Call of Duty series.
Also almost any game, that has cross-platform gaming.
I there's a game, which is out on Mac and Windows, it's highly probable that the CD-Keys are interchangeable.
At least on virtually all sorts of games, based onto the Quake™-Engine.
I can't remember if there was
ever any game, sold out for Mac and PC and got cross-platform gaming whose serials
weren't swappable.
The main thing which causes things like this, is - it isn't almost possible to build up an online system which handles 2 types/sorts of serials within one netcode.
Therefore the devs integrate that only thing, but on two sides.
In this sense
Smartcom