We have over 20 instances of Backup Exec 11d server, but have recently purchased two new licenses of BE12.
We're not ready to upgrade to BE12 across our environment. In our case, is it legal to install 2 old copies of BE11d using existing keys, until we're ready to upgrade everything to BE12d.
We do the same thing with Microsoft Windows Server 2008 keys until we're ready to upgrade, so I would think it would be the same with Symantec.....