This is a Windows system installed file with Windows File Protection (WFP) enabled.
diskcopy.dll has 37 known versions, the most recent one is 6.1.7600.16385 (win7_rtm.090713-1255). The average file size is about 1.44 MB.
Copies the contents of the floppy disk in the source drive to a formatted or unformatted floppy disk in the destination drive. Used without parameters, diskcopy uses the current drive for the source disk and the destination disk.
(Note, the behaviors below are for all versions of diskcopy.dll, select a unique version for details.)
Located in the registry at 'SOFTWARE\Microsoft\Windows\CurrentVersion\Shell Extensions\Approved'
United States installs about 47.56% of Windows DiskCopy.