Time difference on reports

Summary

A time study is being done within our organization on one of our elearning courses. It has been found that a 'few' times have changed by one hour on some of the employees.

Content

Has anyone encountered where the completed time stamp on a report pulled at one time vs. being pulled a few months later (same report) was an hour off? This is not happening to everyone on the report, only a few of the employees. Thoughts as to what might cause this occur?

Thank you in advance.

Kind Regards,

Dena Ridenhour