Build something into a new version of the installer which automatically cleans up the registry entries before installing the newest version if any older version is already existing.
REASON FOR CHANGE:
Customer has had problems getting plugins to work on some client machines after upgrading from an older version.
As a workaround, they found that uninstalling the old version, completely removing registry entries here:
and then installing the latest version works.
To save all that work however, customer is hoping for a new installer which will completely remove any bad registry entries when upgrading from the previous version.