Transitive Component Removal Problem

I have two mutually exclusive transitive components (based on CPU technology)
in my MSI database. During reinstall, if the technology changes, the old
technology DLL is uninstalled and the new one is installed. Everything seems
to look good at that point.

However, during subsequent uninstall of the app (REMOVE=ALL), the new
technology DLL is left on the system. What could cause this?

The components have different GUIDs with mutually exclusive conditions. The
DIRECTORY_ columns are different because while the parent directory and
target directory are the same, the source is different because two separate
folders are used to store the two different DLLs.

Thanks for any help.