short version: the games you already own are "lost", but the rest can be redeemed

long version: every game that you dont already own is activated on steam. you do not get a refund for the games you did already own, nor can you give those away to someone else unless specifically noted (for some specific packs, it works. but its rare, so you can generally just assume you cant)

the key you get is only redeemable once. no matter if some games of those packs are not activated, the code itself counts as redeemed, and you do not get a new code for the excess games.

It was likely pre-purchased and sent via email to the gifter's own address. The link to the key will then be forwarded or re-sent to the winner.

A.R.E.S.

Atom Zombie Smasher

Capsized

Machinarium

Swords & Soldiers