Regarding the issue you are having as default, you should be able to reload the device backup configuration when the device is having the same product code.
You can refer to this link for more information: RUT955 Administration - Teltonika Networks Wiki (teltonika-networks.com)
I am not able to reproduce it on my side: XRwOrcJ.png (1920×969) (imgur.com)
It would be best to try reflashing the firmware of the said device via the bootloader menu and try re-uploading the backup file again.
You can do so by following this link: RUT9xx Firmware via The Bootloader Menu - Teltonika Networks Wiki (teltonika-networks.com)
The latest firmware can be downloaded: RUT955 Firmware Downloads - Teltonika Networks Wiki (teltonika-networks.com)