Thanks for the responses, however this is not the answer.
I had already checked in the smartware.swstor folder and found that only the originally named file was there NOT the renamed version of that file. I was wondering if it had done something clever such as keeping that copy but also another tiny file of changes which it would apply if it were restored. However I don’t think that has happened, instead it just seems to have missed it.
In this session I renamed perhaps 100 files and none of them were backed up when I ran a backup on that disk.
I am wondering whether I have to manually delete that folder and let it do a full backup of it with the new filenames - exactly the sort of thing you don’t want to have to do with a backup.
This is not about multiple copies of files, it is just single files with new names. For example download card from camera, the files have default names, do a backup. Some months later finally get round to rename the files to have sensible names but this time the software does not back them up for some reason.