Using RoboCopy I am copying large sets of files between storage devices and have noticed some strange behavior: On many occasions where the source and destination file are the same, RoboCopy sees the file as changed and copies it again. I have verified that the size and date of the files are the same. I am using the below command. The version of RoboCopy being used is from Vista/Windows 2008.
robocopy "W:\SourceFolder" "Q:\Destination Folder" /E /R:2 /W:5 /NP /LOG+:%1 /tee /fft /purge
The /FFT switch used here often fixes this problem - but not here - (as in these pages addressing the same question: Robocopy falsely marks files as newer which itself refers to Robocopy Incorrectly Detects Files as Newer When Copying Between Different File Systems)