You're right. I have no idea what it's for, but I'm guessing for distinguishing between deployment images. I'm certainly not going to get too concerned about it.

The issue with the microsoft account was not unique IDs - tons of unique things on a machine.... it was a unique thing tied to an account and shipped to remote places.

TIL.

    /var/lib/dbus/machine-id

    /etc/machine-id