did the update update the old update or is this the same update?
No, The update didn't update an update that already exists within an old update, the new update added new stuff which is the definition of an update that is about updating a game and adding new stuff which is the whole point of an update!
Whoever edited the changelog added the old update which was already in the game from an older update (v21.8) and didn't add the new update's changelog which was implemented this update! (v21.9)
....xD
Here's the new update's changelog which was implemented this update by adding a whole new bunch of stuff which is the whole point of a new update!
Bro did you have a stroke or something?
Good luck understanding what I've wrote! xD