I am not sure how to word this. I have noticed that some mods have multiple accounts across the fediverse that have the same name and those accounts are modding in the same community. Take for example c/wnc where I mode. If I went over to piefed and crated an account name profthadbach there and add that account as a mod to c/wnc. I am sure that is cool because I have seen it a bunch. Now my question is if I create a community over at piefed called c/wnc and I post some article there do they show up in the lemmy.world c/wnc community and vice versa?
Simply put, yes. In the same way subdomains are independent of eachother (for example balls.microsoft.com vs balls.apple.com), communities in different instances are independent of each other, even if they share the same name. That’s because a communitys full designation is, for example !asklemmy@lemmy.world
As for the multiple mod accounts on different instances, this is often because the mod-log and reports often don’t federate properly, so it is common for mods to sign up an identical account on the instance of a community they moderate.
When it comes to creating identical communities, first thing you need to ask yourself if you should. Sure, if an identical community exists on a different instance, but it’s dead, it shouldn’t be a problem.
However, when there’s already an active community, it’s better to join and contribute to that one, as fragmentation isn’t really helping anyone in particular or the fediverse in general.
I feel like a lot of people don’t appreciate that instances are different communities, though. A new user may not see the difference, but the Ask Lemmy communities in .ml and .world are different based on the people who use each. If Lemmy grows, I can see the various instances becoming more distinct, not less.
Isn’t the point decentralisation though? If everyone uses the same community to avoid fragmentation that harms decentralisation. I know it’s a tradeoff and there’s no easy answer besides a rewrite of Lemmy to allow grouping communities on different instances or something like that, though.