my iMac has a Macintosh HD and a Macintosh hd 2

This sounds weird, but are U sure that there are 2 of them, and are they connected to each other?

you can also call apple or apple support, but it should not be a problem. Just use the 2 TB, and leave the 2nd one aside until you need it

Yours was possibly a BTO (build to order) machine? Because the option to have a regular hard drive PLUS an SSD drive (solid state drive) was available on mid 2011 machines - see the specs here:

http://support.apple.com/kb/SP623

So, go to the Apple and click on about this Mac and check the hardware configuration.

The other possibility would be that the seller removed the Super Drive and installed a second hard drive instead.

Well, it appears that you have exactly what I thought: your hard drive #1 is the solid state drive (very fast) and has the OS and other files on it. The hard drive #2 can be used for storage - like movies, videos, pics, etc. Since your "main" drive is smaller, once you get videos, etc, I'd direct iPhoto, iTunes, etc. to use that second hard drive for their storage (library), i.e. the iPhoto example here:

http://support.apple.com/kb/PH2506

I don't have any games so I can't answer that question; I would think you can (as long as you can link to that folder from within the app - you should check the support site for your game and/or ask a question there maybe. Or, hopefully someone who runs this game will chime in here.

I suggest that you rename your HDs to something that makes sense to you and not use Apple's default names. Really simplifies things. E.g., I've partitioned my HD and have these volumes:

SnowLeo

Lion

Docs

DMGs

SLBU

LBU