From my experience this happens when the original file attributes can't be written or differs to the backup target: I was doing backups to a ntfs drive with compression enabled but since source files where not compressed they were getting duplicated.
I've noticed this prior to anniversary updated and did not try using a network drive as a backup target, i've not tried other scenarios as file history is now working for me.
btw: i own a synology nas and I created an iscsi target for file history, doing so allows me to hard limit backup space.
Well that makes sense even though it is STUPID. Is it true of e.g. indexing properties also?
If only Microsoft would take note and fix this then this would be an excellent backup tool. But until they do its a useless waste of space.