Backup jobs that recur on the first day of the month may have duplicates.
A custom backup job is created that includes the option to back up on the first weekday of a month. When selecting this option and also specifying a start date, the system incorrectly creates 2 jobs, one for the start date to recur monthly, and one for the selected date to start monthly. The jobs incorrectly share the same ID, so deleting either job will delete both.
To resolve this issue, upgrade your appliance to version 10.1. and recreate the affected schedule using the desired options.