There are definitely ways you can back up the backup, it’s pretty easy to simply move or copy the folder it’s in - I’ve done it plenty of times. but I don’t back it up, realistically speaking the odds of something happening to my phone and my computer at the same time are very slim. If something destroys them both, I probably have bigger problems on my hands

if that’s a genuine concern then a cloud based backup is probably the more ideal option. I like that local backups are totally secure, reliable, fast, and let’s not forget free.