I have tracked it down, and it happens when the backup fails.
In pre-2.0.8.0 versions, it will not send any metadata, just the error messages.
This is interpreted as timestamp 0, using Unix EPOCH, meaning 1970-01-01, or ~55 years ago.
I expect a fix to arrive soon.
Not sure I follow. Is this caused by multiple backups being grouped by the same machine id?
Yeah, that would resolve everything
The only open-source solution I know of is the dupReport monitoring solution, which is based on email reports.