No need. Multiple communities provide redundancy against instance failure, just like instances provide redundancy. If .world is dead tomorrow for whatever reason, even temporarily, I’d post an article here, or vice versa. People subscribed to both would see my post in either case. If I were more diligent, I’d even cross-post to both when both instances are up. Then none of my posts would be lost if one of the instances goes. Subscribing to multiple communities of the same name/type is the norm on Lemmy. There’s no need for same-name communities to be unique, quite the opposite.