I have an original half-life game box. I also have a platinum half-life box (half-life, blue shift, opposing force and counter strike). So, I have 2 half-life CDs, one from my original box and one from my platinum box.
I also have half-life 2.
I see all these games in "My Games" under Steam.
I installed the platinum and used it with Steam. So, I hope that the CD key that is locked to my Steam account is the CD key from my platinum CDs and not from my original half-life CD.
Then, I will be able to sell my original half-life box without violating the Steam's license agreement, which I'd rather not do.