Hello,
Refer to the following technotes for additonal information that will explain the way backup exec handles media, chooses them for backup jobs. The docs also talk about the way Overwrite and appnd periods work:
http://support.veritas.com/docs/192265
http://support.veritas.com/docs/237374
Revert in case you need further details on this or if the issue persists.
Note : If we do not receive your reply within two business days, this post would be marked ‘assumed answered’ and would be moved to ‘answered questions’ pool.
Regards.