I agree that this looks annoying. But maybe the trick is not to think of it as the same article as being posted three times, but rather as the same prompt being used to spark conversations in three different communities. If you find that you see substantively the same content in multiple instances, both in terms of thread starters and ensuing conversation, then maybe that’s a sign you can safely prune the communities you subscribe to.

I reached the same conclusion on reddit where I would see the same article posted to related subreddits, eg news, politics, uspolitics, bipartisanpolitics, neutralpolitics etc.