At completion of rename job keep original

It seems after running a rename method on a folder full of files that the
Filename stored in <ExifTool:Filename> is updated to the new Filename that the file was just assigned. I would like try and have the file keep only its original Filename. If I can accomplish this it would be greatly appreciated. Thanks,
Reply to #1:
The Filename tag of ExifTool is actually not an embedded metadata field. It is instead the filename itself. That means the value of the field will always be the actual filename and not a previously held filename.