LCAWC: Hmm, I too was offered a special sale for a game I already own. I understand some people re-buy games to gift to friends, or unscrupulous individuals buy extra copies to scalp and profit off of, but not everybody does this. This is already reminding me of the Insomnia Sale, neat gimmick in theory, awful idea in reality.
nijuu: I think someone said you can only buy one copy . Also many people liked the Insomnia sale :)
I personally didn't like it, I ended up only buying a couple games during it because I never managed to find more games I wanted when they were on sale. Plus I never got any of the free game offers despite clicking the claim button the instant the free deal went live, I'm guessing Russians/Chinese/script-kiddies/etc. figured out how to gank them all. Just a frustrating experience, doubly so because I wanted to give GOG more money but couldn't.
Anyways, I manged to get a deal today for a game I don't have, so either I got lucky or GOG tinkered with the algorithm for how it picks your deal. Huzzah!