Apparently I have an issue with my library. A steam Game (GTA San Andreas) is displayed twice. One of its instances can't even be installed.

I made a topic on that particular matter, but literally no one had anything to say about it. After doing my own research, I came to the conclusion that the cloud data is corrupt. The problem is, we have no way to wipe it.

I issued a support ticket on November 26, and after 3 weeks, it was still unanswered. I figured I may have completed a form the wrong way, so I issued a second ticket on December 20.

We're close to 2 weeks since the second ticket was issued, and I still haven't got a response.
Am I missing something?

I'm not expecting an instant fix, but they could at least acknowledge my issue and say something like "we're working on it"...

Oh no, it displays twice.

I don't have SA, but I have GTA III and Vice City, and they both show two instances in the Steam itself. I don't think what you're experiencing is Galaxy's or integration's fault.

I have all of them on Steam. And yeah, now that you mention it, 3 and vice city have the same issue.
Curiously enough, this issue doesn't happen with other games. GTA 4 and 5 don't suffer from this either.
It seems it's only related to the games from Rockstar's 3D era. Thanks. I'll do that. This particular issue isn't really the end of the world.
But I think I have the right to feel frustrated when the support team that's supposed to help people aren't doing their job.
Even if GOG isn't responsible for this, they can at least point me to the right direction, like Randalator did.
If you don't have anything useful to add, just don't participate to the topic.

What I meant was that you (like many other users) have in your Steam library two instances of each of those games. And that situation is simply reflected in Galaxy. It doesn't seem to be GOG's fault.

But I don't have two instances of these gamers. I only got them once.

Sigh. Open your Steam client and check there.