About Vaulting original or duplicate images
One of your most important choices is whether to send original or duplicate images off site. If you send original images off site, you do not have to duplicate images and therefore do not have to configure duplication.
Vault distinguishes between original images and duplicate images as follows:
NetBackup creates original images during a backup job, including all of the copies that are created concurrently by a backup policy. NetBackup can create up to four copies of an image concurrently during the backup process; all are considered originals.
If you create multiple original backups in a NetBackup policy, assign the primary copy to the volume pool for the media that remains on site. And send a copy off site.
Duplicate images are the copies that Vault creates. A Vault job reads the primary backup image and writes one or more duplicate images concurrently. The Vault job is separate from the NetBackup policy job.