@Gre***
that entry stamp has nothing to do with the re-entry permit being valid or not, ;) It WAS valid when they entered the country and because it was only a single re-entry it was marked used :P and that's why they got the Non-RE stamp
I checked my entry stamps and they're all Non-RE although they're just sucky hand written ones not stamped nicely like
@Tr***
's was ;)