HypersomniacLive: I have no idea, and am not inclined to research it.
My previous post to you was more in relation to G2A being somewhat of a red flag here.
tinyE: Well it is a Red Flag obviously but I don't think in this case. I seriously doubt this guy is up to anything. He just got the sites confused. It happens.
It's still a "Red Flag". Not necessarily being the original buyer's fault, but that doesn't mean that this GoG code might not be later revoked (if it hasn't already). And if you go to G2A and click the seller link for the cheapest seller, click negative ratings for Ggamez, 2 of the first 5 ratings claim his Mount & Blade: Warband GOG.COM Key GLOBAL codes do not work...and this is a buyer with a 98% positive rating (which includes 2113 bad codes in his 113231 ratings).
And if you click through his 100,000 "positive" ratings, looks like someone for some reason has bought hundreds of Witcher 2 codes from him (same user). Since they load 5 at a time, I didn't look further, but someone found a way to pad his ratings quite a bit so he can sell bad codes.
This is why you do not buy from G2A Marketplace or accept codes in trade from people who do.