Marvyn Cox was 'German' champion, he also wore the German flag in a World Final!
This dodgy 'dual nationality' really does make sport look daft, and it's not just speedway either. There have been numerous footballers over the years who have played friendlies or junior levels for one nation and full competitive internationals for another.
It's daft, Play/ride for where you or your parents were born and be done with it, although ideally it would be nation of birth only, but that would scupper riders like Mark Loram as Malta haven't got much of a speedway team!