The only thing I can think of, is that by importing the file back to the new db, the content of the dump file is encoded again. And that's why those two cryptic chars, are now four. Ü (1) -> Ãœ (2) -> Ö (4)
Ups, last one are 5 cryptic chars ... it was late ;-) So, I am unsure if my theory is correct.
Best regards, Kai