Removable media that you can take away from the machine/device satisfies what is acceptable backup. Even moreso when you have 2 backups you carried away.

When stored and handled proper, you'll get many years of safe backup from your media.

One simple suggestion. Simple backup tends to work best. That is, if I erase a DVDRW, then write files to it with simple CD/DVD recording software in a closed session without "backup software", then the disk and files are readable across many machines, OS and platforms.

Bob