SEP can uninstall both competitive products in a single package via SEPPrep or the older competitive uninstall tool.
Why bother having to distinguish what is installed previously?
SEPPrep works by the add/remote control program entries... As long as the entry in your control panel matches whats in the ini file, it will be uninstalled.
The older competitive uninstall uses template files calling the msiexec /x {guid} of the respective products.