Hi, the backup bios on these boards is not accessible to the user [no bios changeover switch], only the system can access the backup and only then if the main bios fails to boot.
Then on the next restart, the system boots the backup and overwrites the main with the contents of the backup.
Also, it's not stated in the manual for this board, but I'm sure I've read in another manual that if after flashing the main to a newer version and the boot was successfull, that the backup was then also updated with the contents of the main.
Which leads me to a somewhat risky thought! If this automatic updating of the backup bios does not
occurr on your board and it keeps it's original contents forever and you want to save a copy of it, then you could...could....[I really shouldn't even mention this!!] open a bios file for that board in a hex editor, modify the file, upload it, the boot will fail, restore from backup would kick in and viola! your main bios now has the same version as the backup.......feeding lions with bare hands can result in serious injuy or death!!!