Just a direct link to a Shark Tank story at Computerworld. I can’t improve on their own title so I just copied it.
I was involved with a company that suffered a similar loss when it turned out that operators were re-using the same backup tape every day, but as I recall that was three months of backups lost and was discovered when an errant script performed an rm -r from the ORACLE_HOME directory while the database was open. Happened on a Friday, of course.
Ah, happy days.