Multiple Instance of the same Backup set show under storage tab
Double Click on the Device under Storage Tab and check the Backup Sets. If the same backup set (on the same destination i.e. Disk or Tape and backup time ) appears more than once then the Issue matches to the one mentioned in this article. This Issue does not cause any problems during restore.
This issue is resolved in Backup Exec 2014 or later versions.
: Symantec continues to focus on the current release and future releases, there are no plans to address this issue by way of a patch or hotfix in earlier versions of the software at the present time. Please contact your Symantec Sales representative or the Symantec Partner for upgrade information including upgrade eligibility to the release containing the resolution for this issue. For information on how to contact Symantec Sales, please see http://www.symantec.com