mmm,

I foudn the following about protected files.

Protected File List

WFP protects files with the following extensions that are installed by Windows: .dll, .exe, .ocx, and .sys. In addition, the TrueType fonts Micross.ttf, Tahoma.ttf, and Tahomabd.ttf are also protected.


At the end of the Windows installation, WFP runs a scan of all protected files to ensure they have not been modified by applications installed through unattended installation. WFP also copies verified versions of these system files to the cache directory. When an application attempts to replace a protected file, WFP can restore the original file from the cache directory.

To specify the location of the cache, use the following registry setting.
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With deleting duplicate files, you really have to be careful. If anyone cares to add anything else to this, I'm listening.
Welcome to TZ by the way!