CS6 covers a few Adobe products. The actual application installs are different for each OS. You might be able to get a couple of copies by contacting Adobe and telling them you have a PC and an Apple laptop that you use on the road. I doubt they would supply you with both installs but you can try.
Since the first Adobe Creative Suite (CS1), the boxes for both systems are separated.
The Adobe Design Collection is another story, there you would get the Mac and Windows versions aswell in one box or at least both versions were on the CDs/DVDs.
The Adobe Design Collection is another story, there you would get the Mac and Windows versions aswell in one box or at least both versions were on the CDs/DVDs.