I think users are still having trouble with the mental model for browsing Lemmy.
The first interaction with the service is already fragmented - you need to choose where to create an account and start browsing. Even though you can browse communities from other servers, people are now seeing them through the lens of “fragmented” “my server vs other server” and that creates the illusion that these duplicates are somehow a huge issue.
But duplicates can actually be quite useful - a community called “memes” on Lemmy.world could attend to a different audience than a community also called “Memes” but made in an instance entirely in French.
Also, if two instances have two communities you enjoy, with the same name… Subscribe to both? Nothing stops you from doing that. It’s okay. Reddit had “me_irl” and “meirl” which were the exact same, but with different mods, a relatively similar number of subscribers and quite honestly the same content. I didn’t know the actual difference between the two, and I still do not know - I just subscribed to both and kept getting depressing memes to cry before going to sleep. No issues.