windows 7 - How to back up only newer files

I wrote years ago a script using XCOPY with parameters /E /D /Y /V /R /H
that allowed me to back up newer files to my dropbox having always everything updated.
Since I upgraded to Windows 7 and 10 this doesn't work well since Windows 7 changes the date of the file when it copies it making a big salad of data modified/created (sometimes files get modified dates earlier than created after copy)
I so that with ROBOCOPY i can maintain a duplicate directory, but updating always ALL the files, and that is slow (I have 1Terabyte to maintain)
Is there a way to force the file timestamp to keep constant when copying under Windows 7 and up? or some copy program that can find out what has been really modified and update only the modified files?
Thanks
Eli Jacob