The modification dates of files are changed when copied to a Mac OS X Server 10.1.5 via Apple Filing Protocol (AFP, or Apple file service).
Symptom
File modification dates are changed when files are copied via AFP to an Xserve. The last modified date is changed to the time the file was transferred to the server.
Note: The modification date of the files on the file server are changed, not the files on the client.
Solution
Mac OS X Server 10.2 or later resolves this issue.