Ok, I have just checked it again and now I have a key for Mp mode as it was intended to be, I guess. It was probably a bug.

There's a key available for it that's not a dupe, so:
Granted.
I'm afraid there actually aren't any current copies for it. The key Bela just spawned (given by gixgox) was...somehow the same exact key that's been popping up.

It looks like the games spawn a second usable key, but after the third, it glitches out and gives the SF88 one.

All three games give me a code that says that it's already been used. I gifted them to people who redeemed them, so that tells me that the old keys that were originally there are still there, as opposed to multiplayer keys.

So when i checked my copies of Xenonauts, Sunless, and Rime, they all had expiry dates within the month.
Does that mean that if nobody redeems the codes, they are rendered useless? If so are the donated ones for this giveaway going to be taken off after the expiry date?

If the games expire that soon, i might just start a thread for people to give this sale's codes away for people who missed out on them. I would hate to have a ton of games donated here just for them to disapppea soon after.

You could use this thread: https://www.gog.com/forum/general/the_expiring_codes_clearinghouse_thread

Thanks there'a a similar more active thread too.

I had the same situation yesterday (and about an hour or so ago). So I decided to send that additional key to zeogold. Now when I check all three games in my library (SoC, CS and CoP) it show me a code for multiplayer. Like this: QWERTY123UIO4567

From what I understand, you redeemed a second key, which gave you the used key, which has now been replaced with a multiplayer key. I bought the game and donated the second keys, which still show in my library under "serial keys", so you get a multiplayer key and I don't? It's a good thing I don't care about multiplayer. This whole situation is very strange.

Well... I sure am glad we have The Puzzlemaster working this case! We need top expertise to unravel such a convoluted thread.
I'm pretty sure he has a map of the world filled with lots of pins connected with strings that surrounded by avatar pictures and game codes. Zeo himself, of course, is smoking his pipe by the fireplace and does not take his eyes from the map, trying to crack the pattern that surely must exist.

May I have Primordia, please?

I like to see the love for STALKER. Great series.
Shadows of Chernobyl has one of the best atmospheres in gaming, and in certain points the tension is palpable.
A warm recommendation: play it with the Zone Reclamation Project patch! It fixes hundreds of bugs and can enable little comfortable mods that don't alter the gameplay but make things nicer, like the "continue" button at the top of the start menu ot the bedroll.

Zeogold gave me a key for STALKER - Clear Sky one month ago from Aramandur, and he gave me another one for Call of Pripyat yesterday (the SF88 one) from Jungle_Falcon.
Both had an extra key under the "more" button, that I checked yesterday. The one from Clear Sky one month ago had already been redeemed, while the one from Call of Pripyat had not (yesterday), but has been redeemed since, so someone must have redeemed it yesterday or today.

I would also be interested in a Shadow of Chernobyl key (so that I could play the series from the beginning). If granted, I will give back the extra key with it, but I don't know if it will be a used and / or unique one.

This is one big mess. Tell me how you want to handle it zeogold.

thanks zeogold and gixgox
i'm glad that i could be the experimental subject

Yes I redeemed a key for CoP from this giveaway (from Jungle_Falcon), and it granted me SF88 key which was redeemable as well. And now it has been replaced with a multiplayer key, which is unnecessary (you don't have to use it in Mp matches now), as far as I know. At least it works for Clear Sky, which I have checked just now.

I just found out that the GOG code redeem system can tell you that a key is valid even if it's invalid. asd appears to be a valid code for The Witcher 3: Wild Hunt and dfa appears to be a valid code for The Witcher 3: Wild Hunt - Expansion Pass, but attempting to redeem either code results in the error message "Apologies, this code no longer appears to work. If you believe this is incorrect, please let us know." I guess you learn something new every day.