I can’t answer, but I am going to mention that there are a lot of partitions on an AGX Orin. Jetson’s don’t have a BIOS, so some of that is the equivalent of the BIOS, and other parts are boot content. The rootfs (the actual operating system, or “APP” partition) depends on that content being set up correctly. If you say to flash, but to “reuse the existing rootfs”, then your o/s clone is still used, but the other content is flashed to that release.
I don’t know about the backup/restore scripts, but my guess is that you need to restore to the second Jetson via a full flash, but reusing the rootfs (which is from the clone). You might need to specify the size of the rootfs/APP partition if it isn’t the default. The part which some people might get wrong is that the release of L4T (see “'head -n 1 /etc/nv_tegra_release”) used in the flash of the clone must be the same release as that which is on the original system (note that the JetPack/SDK Manager release version is tied to the L4T release version, so if you match either you are matching the rest of that). When you flash normally, but reuse the rootfs, you are making sure that the boot content is compatible. If you avoid flashing that other content, then probably it is going to be incompatible.
One twist is that the same rootfs might work on slightly different models if you perform that full flash since it updates the boot content. Even if you have the same “model”, sometimes there are different carrier board revisions (I don’t know about Orin, but there might be a revision by now on AGX).
Someone from NVIDIA would have to answer if the backup/restore script will reflash the non-rootfs content, and if it handles different board revisions. If not, then having the rootfs clone would still allow you to command line flash the other AGX Orin with the “reuse rootfs” (and setting the image size) on command line.