Can you only activate some games from a Collection?

I bought the Frozenbyte collection (http://store.steampowered.com/sub/16533/?snr=1_5_9__403)
I wanted to get the DLC for Trine 2, but for a few $$ more I get a bunch more games. I already have Trine 2, so would I be able to gift the rest of the games or does everything get activated if I add it to my library from my inventory? I am not sure how that works, and what happens to Trine 2 since I already own it? Thanks....