TL;DR Don’t have a HAOS image on both a SD card and a NVME SSD in the same RPi 4 system
This might be obvious to some and helpful to others, but it turned out for me that you can’r restore a backup onto a system which has multiple HA system images visible. In my case, I was transitioning from a SD card to a NVMe SSD.
After writing the HAOS image onto the NVMe SSD, i mistakenly swapped the RPi OS SD card back to a HAOS SD Card, to provide a fallback in case the HAOS SSD wouldn’t boot.
The system rebooted fine etc, and all was well until I attempted to restore the HAOS NVMe SSD with a prior backup. Attempting to restore resulted in ‘Duplicate OS Image…’.
This link describes more fully the issue: Duplicate Home Assistant OS installation - Home Assistant
Once I replaced the HAOS SD card with the RPi OS SD card and rebooted, HA came up off of the NVMe SSD as expected, and I was able to do a full restore from a recent HAOS full backup.
- Installation methodHome Assistant OS
- Core2025.12.4
- Supervisor2025.12.3
- Operating System16.3
- Frontend20251203.3