As requested by some users: ‘old’ style now accessible via https://old.lemmy.world
Code can be found here: https://github.com/rystaf/mlmym , created by Ryan (Is he here?) (Yes he appears to be! @[email protected] ! Thanks for this awesome front-end!)
Connect for Lemmy used to throw error, giving you a illusion that posting a comment failed, so you click again. Rinse repeat.
This is why there are duplicate posts/comments.
For me problems were gone when I switched to Liftoff app.