@robryk I don't know. I use lieer to sync to local Maildir with notmuch and don't do IMAP anymore.
But maybe? I guess it depends on the client. Notmuch for example dedupes by message-id, so reading one copy reads all of them. So if you sync locally, then import into notmuch you'd get good behaviour again.
@robryk people who access email over imap @djsumdog @wikihow