So I've created a new fresh install on a separate usb. I have now booted to that, and ssh'd in to see my drives.
I only have one of the mmcblk1p2 (as opposed to 2x similar mmcblk). the disk one here exists; I have renamed that to libreelec_disk.
If you have correctly performed a fresh install of LE 8.0.0x, you shouldn't have to rename either partition.
You should have LIBREELEC and LIBREELEC_DISK
So I just copy one "disk" partition to the other "disk" partition and that is enough?
You'd be copying from the "disk" partition to the newly created LIBREELEC_DISK partition (on my USB sticks the partition name is all UPPERCASE, might make a difference)
There's no point in copying anything from the old boot partition, since doing so would be overwriting your new LE build with the files you are having difficulties with