Restore from one Mikrotik to another error

Hi, I have 2 PC Intel x86 Mikrotiks. I have made sure both are running version 2.9.51. One is production and the other a hot spare. I backup the production and ftp that file over to the spare. When I restore the backup file I get this error:

Couldn’t restore configuration - Incorrect file size (6)

Can you actually restore to a different hardware? I have successfully restored to the same PC.
Cheers

if you change hardware, better use export/import commands…