@shadowfax From what you have described Kevin I think you would need to double check the backup location - as clicking “No” to replacing files would usually result in Windows creating a “copy” version (same file name but with something different at the end) OR it will not have copied anything
Coincidentally I have just finished backing up ALL of my family photos and videos to ONEDRIVE (Cloud)
It took AGES to upload but I do have a sense of security if the worst were to happen
The reason I mention this is that ONEDRIVE allows you to chose any folder to be your “OneDrive” folder for syncing with the cloud. I was able to put this folder on an external drive so that I have everything backed up in 2 places (external drive and cloud)
I then use Microsoft SyncToy to sync this folder to ANOTHER external hard drive - so I have an exact copy of the data in 3 locations
SyncToy is free and easy to set up “folder pairs” to keep folders in sync (an automatic way to do what you are currently doing manually)
I also recommend Macrium Reflect for doing backups of drives
There are lots of ways (and tools) to create a workflow that suits you so it is worth spending the time to figure out EXACTLY what you want and then identify the appropriate tools - bearing in mind data is not considered safe unless it is in 3 separate locations