Should be fine as long as your have 2 different windows 8 keys for each pc.
This was a bigger problem in XP and even Windows 7, as if you had say, a Dell PC with a Dell OEM key on it, you would need a "Dell" version of XP or 7 to use, or the key wouldn't work with say an OEM or Full version of Windows. Makes reinstallation work a headache sometimes at my shop, as someone comes in, of course has no discs, but still has the key on the side of their PC. Using a copy of Windows downloaded from MS or digitalife, etc, that key wouldn't work. I would have hunt down a "Dell" copy of windows.
I haven't done much with Windows 8 in terms of name-brand PC's in my shop yet, but I'm hoping they opened up the licensing more so the keys are more generic.