Superduper changes dates
 

I have a set of set of folders. Each folder contains files pertaining a year, 1957-2011. Although the files were created by scanning docs, I would like the creation and mod dates for each file to correspond to the proper year (Jan 1, 19xx 13:01). I can change mod and creation dates in Terminal using touch. When I change the dates, I delete the old files from the backup and replace with the updated files, so that they should be identical. However, for the folders containing from 1957 to 1969, each time SD does a backup the files in these folders revert to creation and mod dates of Dec 31, 1969. The process is completely repeatable. Any suggestions?

Unix file dates start then - it's the earliest date we can set.