Incremental backup saved with wrong date and time.

I did compete backup of my laptop to my WDC Mybooklive network storage device last Thursday and all is ok when I inspected the backup file directly in the folder on the WDC drive.

Today, on 31/8/2014 (UK date format) I performed a daily incremental backup of my Outlook email folder to the same drive, in a different folder for logical and housekeeping purposes.

When I checked the backup as I do occasionally by inspecting it on the WDC drive itself, I noted it has saved today's incremental backup with the wrong date and time. I performed the backup just after 1200, but the backup is labelled as having been performed on 14/8/2014 at 16.56. I did another backup a few minutes later and when I check the backup again in the folder on the WDC it says it was performed on 14/8/2014 at 1703 (a few minutes later).

The time and date on my W7 laptop in correctly set, and the confirmation email that Acronis TI13 sends to me after completing the backup also has the correct date and times on it.

I am somewhat mystified.