
In the OP you are looking at two different /c/science communities, namely !science@lemmy.ml and !science@lemmygrad.ml. So the “same” posts you are seeing are just crossposts by the same user. On this site you can see the outgoing federation status (for lemmy.ml in this case). Hexbear is listed under “up to date”, and for lemmygrad as well.
Such problems can also happen because of language settings or user blocks. So best view these post listings while logged out or in a private browser window.













I just commented here on that thread, its really not a big deal. Using regex for string matching also sounds fine. On the other hand Piefed is a smaller project than Lemmy, so it has less testing and reliability. In the end it depends on your own requirements whether Piefed or Lemmy is better.