@mikedev Is the problem with Mastodon related to its limited support of Add activity? It's not just Mastodon, the entire (micro-)blogging part of the fediverse still doesn't support FEP-400e, and also Lemmy & co who implemented FEP-1b12 instead
Sending duplicate activities doesn't sound very bad to me. Lemmy still does that, even though some of their groups are quite large.