Upgrading Backup Exec windows agent

Hi

If I have to upgrade the backup exec windows agent from BE 2010 to BE 2012 SP4 do I need to first uninstall existing version and then install 2012 or will it upgrade directly from 2010 to 2012.

I have the following OS wherein I will be upgrading

Windows 2003 ,Windows 2008 and RHEL 5

These clients will be pointing to a different Media server post the upgrade. 

Thanks