Games that give extra copies upon redemption?

Aerena and some versions of Interstellar Marines too.

Interstellar Marines - Spearhead Edition
Aerena - Clash of Champions

Starforge Founder Club Edition gives a second copy of Starforge Founder Club Edition.

Aerena is free to play now. Intersteller does that.

Frozen Synapse does.

"The Ship" explicitly states that it's a 2-Pack (there's also a "normal" version that doesn't give extra copies), redeeming the "original" The Ship even gives you 2 2-Packs (so 5 copies total).
If you go there, you need to list all the games that can come in x-Packs.

Gun Monkeys.

Achron

Starvoid