People have the double amount of possible Achievements

I've noticed in the last few days, that I have many games, where some people have the double amount of possible achievements ans points in the game leaderboard.
Is this an bug or how is that possible?

In this Leaderboard: Hue Gamers
the person on the 1st place has 26 Achievements unlocked, but the game has only 13


same here: Adiel_Ch's achievements in Forza Horizon 4
322 of 178 achievements??

The Hue leaderboard looks normal to me?
https://i.imgur.com/w2Wfez8.png

I fixed Adiel_Ch's achievements in Forza Horizon 4 however.

You can find a few others at the top of the completion percentage leaderboard. Something tells me that the 157.5% completion percentage is incorrect.

completionperc

The Hue Leaderboard is normal now, there was an player who got 26 from 13 achievements, but the account doesn't exist anymore.

Is this an bug with the achievements? I've got several examples, where an player has more achievements, than possible

e.g.:
Seny's achievements in Dead by Daylight
264/230

JonathanKrane's achievements in MONSTER HUNTER: WORLD
156/100

Saucy Jack's achievements in Forza Horizon 5
248/124

I'm just wondering, if this is an bug from scanning

Oh, weird. Definitely a bug then.

Looking into this now

Looked quite solved for a while. But now there are a bunch more. DeGaBROs Gaedi, Witheredness, pav, MANBANMAN, Draykoth and BAZONA all have a bunch of games with significantly more achievements than available on several games.

I just got 4 out of 2 on Viscera Cleanup Detail: Shadow Warrior. Don't think I did anything weird, but I do also have those same achievements in the base version of Viscera Cleanup Detail.
Viscera Cleanup Detail: Shadow Warrior Gamers

And I noticed two people on Horizon Zero Dawn Complete Edition have 158 out of 79
Horizon Zero Dawn Complete Edition Gamers

I got 26 of 25 in Placid Plastic Duck Simulator earlier today. Probably because it counted my new achievement in a dlc but didn't update the denominator. In the same scan my recent games became what I played last week.

I just performed another scan after earning some more achievements and now got 32 of 25. It should be 32 of 32. My Two Point Hospital numbers also became messed up andmy recent games are still a week old.

I'm having the same problem. I reinstalled some games that I had completed before being registered in Trueachievement website because they didn't appear in my game list. Now they appear but with the double amount of achievements, I would like to solve this but I don't know how. The scan doesn't provide the correct amount of achievements, no matter how many times I run it.

Same problem, I have 47 of 40 in Plantera 2: Golden Acorn.

Not personally affected, but stumbled across this profile that is: Dallas_wolfdog

Just happened to see the CSD series leaderboard where they have way too many achievements—240 out of a possible 154... Cook Serve Delicious/leaderboard Series