I believe he wants to reset the date\timestamps on the copies to the originals not update the modified dates on the originals !! -- Not sure if it still works in WIN 7 but used to use File Date changer - If it does not work in WIN7 I'm sure there are other programs out there that do the same for WIN 7 files.
EDIT : Seems File Date Changer is Obsolete but they now link to BulkFileChanger
which is supposed to work in Win7