SEP Client upgrade retaining old client definitions

After upgrading clients from 12.1.1101.401 to 12.1.2015.2015 and rebooting twice I am still seeing content for the old version in the ProgramData\Symantec\Symantec Endpoint Protection folder.

I am also finding clients that still have client data from the previous upgrade from 11.0.6300. Is this working as intended? Is there a known script that I can run across the domain to remove old definition files? This is especially important on our windows servers as their disk is stored on expensive Netapp trays.