UPDATE: Your post gave me the idea to try link my 3rd party account to
her Google Home account. From there I was able to add the devices to our
home (and moved the duplicate ghost devices to another fake home). The
ghost devices still exist for me, b...
This could give some insight as to where the issue is coming from
because I also have a partner in my home. I checked Linked Accounts on
her account, but she did not have anything linked. My issue persists.
Thank you for the suggestion but this did not work for me. Even though I
clicked 'unlink' following your instructions, my ghost devices still
show as 'offline' in the Google Home App.