mautrix
Equivalent "GUID"s are sometimes split out
When a person you're chatting with has both a phone number and an email address tied to their iMessage, this leads to potentially two "guids" for the same user. Generally I've not seen this be an issue but for some reason today after a restart the bridge decided to switch one person's GUID from one to the other. This caused a new room creation with incoming messages going to the new room, but outgoing messages still went out via the old room just fine, of course to the same chat as seen in iMessage.
On Monterey noSIP.
Confirming that this can also happening if i.e. sending SMS and iMessage to the same number, I think this is a duplicate of https://github.com/open-imcore/barcelona/issues/41
