I discovered this by accident, and with extreme alarm.
After comparing and filtering out literally thousand of photos stored on a drive that could be unmounted, I inadvertently opened Anti-dupl again before remounting said drive. I quickly remedied the problem, but much to my dismay, I discovered my search profile had been completely erased.
I believe one factor is that the search profile is on a drive that was not dismounted, but even so, there's no legitimate reason for the profile to be erased in the first place.
I tested this multiple times.
For the time being, I'm going to attempt to keep the profile on the drive that can be dismounted, so that in the worst case scenario, I'd simply have to reconnect it, but this should not be necessary.