1. Below is the process to Stop View from creating DUPLEX backup tapes?
A sub-parameter of the SARINIT "STORGRPn" parameters, specifically the (unit2-name), determines whether backup tape duplexing is done by View. To STOP duplexing, you would need to remove the (unit2-name) specification from the appropriate STORGRPn definition(s), then recycle the SARSTC task.
2. Below is the process to delete View's knowledge of existing DUPLEX tapes and free up those tapes
Once DUPLEXING is turned off, you can then run the SARPAC process against all of your PRIMARY backup tapes.
When the data is SARPAC'ed to a NEW primary tape, View knows that it no longer needs the DUPLEX copy.
Execution of the next standard backup cycle following the SARPAC process will actually delete the DUPLEX pointer records out of the database. And the tapes associated to the DUPLEX copy will be freed up for scratch.
For more information about STORGRP0 parameter, see here: Initialization Parameter Statements