That happened to me once as well, but I deleted the duped character almost right away... Took some items that were nice and then deleted him. Wasn't very high level anyway, 70-80 or so lol.
We've tried blowing in the memory card, moved it to the other slot, waited some time, deleted the guildcard file, but still same message. It's screwed... Unless my theory works, then deleting the save file is the only thing left to do. Well we're gonna have to do that anyway to test if my idea works.
That rafoie thing sounds really weird btw
Anyway I just thought that somebody on these boards might have 'deeper' knowledge on the save files, thus being able to tell me if my theory is going to work or not.