Install Yocto image and backup

[Jupiter]

Apology if it is an off topic, I could not find proper mailing lists
to ask questions.

I built Yocto Linux kernel and installed Yocto image to MTD NAND
storage in an iMAX6 device, because we designed RO for the kernel and
root file system, RW for applications, we can update applications OTA
but we cannot update kernel and root file system OTA. My supervisor
asked if we need to have a dual NAND storage to backup the kernel and
root file image, if the NAND bad sector occurred in the primary image,
it can be booted from the secondary backup image. I understand where
the concerns come from, but I am not clear if it is necessary or if it
is a common practice to perform NAND backup storage, appreciate your
insight advice.

Thank you very much.

Kind regards,

- jupiter