In reference to this: https://github.com/immich-app/immich/discussions/2463#discussioncomment-5938690
tl;dr - I wiped my Immich install and reuploaded the photos to the new instance using the CLI tool. Now Immich isn't aware that the photos on my phone are the same as those on the server so the mobile app shows the photos as duplicates, one being "local only" and the other being "cloud only" for each pair.
According to Alex it sounds like I just need to edit the deviceId column of the assets table so that all of rows use the device ID of my phone instead of the ID generated by the CLI tool.
Is that correct? Is there anything else I need to do?
Thanks.