NDMP job fail with "job name already exists" even when there's no other Active or Pending job.
A duplicate job may exist in the Scheduler Database.
Rename the job
If running 11.1 or later refer to the kb: https://support.software.dell.com/netvault-backup/kb/214848
As of 11.1, the creation of duplicate job names is restricted through the NetVault Backup/config/allowdupjobname.cfg file