The My Cloud app backup only save Camera Roll photos and videos.to the My Cloud device. The files you backup will stay on the device until you delete then from it – or “something goes wrong” and is why you need a backup of these other than on the device. Right now you second copy is on your iOS devices, so get them backed up to the My Cloud and make a copy of them to another drive you have. and, periodically back them up after you have added more files to My Cloud again.
One thing you can do is since all the files get dumped into the main folder of My Cloud is to set up another set of folders where you copy qnd arrange the same photos and videos into collections like My Trip to Alaska, My Trip to Hawaii, etc. That still gives you two copies, although they are on the same drive, but makes it more convenient to view your photos and videos.
I also recommend you read this:
