Addra or Dama?

Short answer: yes.

Polite answer: This subspecies is called both addra and dama in english.

Yes, nicholas is right.
I believe you're confusing the addra/dama gazelle(Nanger dama ruficollis) with the mhorr gazelle (Nanger dama mhorr) The big difference between the two is that the mhorr has red all on it's upper body and side of it's legs while the dama/addra only has it on neck and slightly further.
Mhorr:

Oh. I was under the impression that there were 3 subspecies. In that case, I've seen both. Thanks for the replies.

This is an Addra Gazelle. The name Dama is sometimes used for the whole species Dama/Addra/Mhorr. Damas are not present in captivity.

What would a Dama look like? I haven't found much to compare the looks of the three.

More or less halfway between the two extremes - however, Dama *may* be extinct.

Oh. That's not good.