tv tuner card for inhome wireless

I hope this is the right spot and I can make my needs clear.

I am looking for a tv tuner, internal or external, that will take two cards from my cable company. I have found one ATI external that will accept one card but not two. I want be able to view one show while recording another, like my current cable DVR. I am not trying to go around my cable company, they do the card intstall and I pay a monthly rental for the card (less than the current box.) Anyone know of such a beast? Thank you for any help.