I have File History set up on my Windows 10 PC to save copies of my files to a network drive every hour. As I understand, it's supposed to only save those files that have changed since the last time they were copied, but it looks like it's copying all files, essentially creating a full backup set of all my files every hour.
Here's an example of a Word document in my OneDrive documents folder:
As can be seen, the file was last modified in January 2014. Yet File History keeps saving a copy of it every hour (except when the PC is off, of course):
That's just a selection, in total I have 53 identical copies of that file. Of course, it's pretty small, but the same is happening with e.g. video files hundreds of megabytes in size. The result is that File History is quickly eating up the space on my network drive.
How can I fix this? Is it a known bug with File History in Windows 10? I've searched online but haven't found any solutions, or even any descriptions of the same problem.