I have the same problem. But that's crap, when you set up many RUT240 you always take the preconfiguration over such a backup of course. If you can not use the backup for all RUT240, you get completely confused. Or you have to change a setting in the backup, you would have to do that in each backup and have a device of each model of the RUT240 on site to be able to create the backup.
Please build an option (under Advanced) to be able to import the backup anyway.