How can I stop duplicate Calendar invites from appearing on my iPhone?

I have a shared calendar with my partner and when she adds events to it, it used to come through as a notification and automatically added to my view. Recently, it was started to also send me an invite from myself on an old email address that is no longer used or linked to any Apple IDs. I have to accept the invite and press okay on her notification to add it to my view. If I try to delete / decline the invite, it removes it from the shared calendar and both of our views entirely, even though I wasn’t the one who sent it. For clarity, my partner doesn’t have this old address in her contacts for me either so not sure where it’s coming from.