I don't think this is an issue tbh.
The full name of a community includes the instance is running on. For this community here the instance is asklemmy@lemmy.ml . If you are referring to community you should include the instance to avoid confusion.
To the issue of duplicate communities: That issue existed on reddit too. Communities with slight variations in the name always existed. Sometimes the owners of some variation of the community just decided to forward their users to a "main community". Sometimes multiple communities coexist. I believe that in most cases a certain "main community" will establish itself as the one that the majority just accepts as the "real deal" because it has the most activity and the best moderation policies.