Hi,
This is automatically done by Windows Installer.For example if the module is shared between two packages the contained DLLs (which have same GUIDs in both package) will be removed only after both package are removed. In this case the Windows Installer Sharing mechanism is applied.
For more details please see:
http://www.advancedinstaller.com/forums ... f=2&t=1159
In your case the DLLs are removed because they are not referenced by other application.
Regards,
Gigi