3 different CD keys

When I purchased Gal Civ 2 via the download, I received 1 serial# that I put in during the install. When I went to update the game via Stardock, it didn't work, but I was able to get the correct upgrade key via email. Although this key works, I was having troubles getting it to work at first (i.e. I was clueless to what I was doing). Anyhow, I had them email my key again, but this time I got a third key.

Basically, what I'm saying, is I have 2 upgrade keys that work, not sure if that is a bug or working as intended and didn't really know where else to post this. If it's not a bug, just disregard this please.