If a user submits a comment and doesn’t see an immediate response from the server, they might submit the comment again. Right now there’s no automatic check for this sort of duplication.

If you’re not sure if your comment has been received, check your profile; if your home instance has accepted it, it should be there.

Many servers have been struggling lately, especially lemmy.world. When that happens, they frequently time-out when comments/posts are submitted, even though the comment/post was processed… the client doesn’t realize and behaves to the user as of the comment/post failed. It didn’t fail though.

Lots of people resubmit without checking to realize it actually worked the first (or fifth) time, resulting in dupes. lemmy.world just fixed a bunch of performance problems and submitted PRs to the devs to fix them for everyone else too. With the improved performance, you should see less of these dupes going forward as the number of timeouts is reduced. But it’s another bug that clients get confused about whether a post went through or not. Maybe that will get sorted soon also.