Man, I really hope they get that figured out for you, and catch whoever took the other badge. It's odd that they'd open it up and take just one--kind of makes me wonder if it's not someone that was planning to actually use it to go to the con, instead of selling it (otherwise, why only steal one? and why open that specific package, unless they noticed it was from Otakorp and guessed what was in it?).
Maybe this is a long shot, but does Otakorp have any way of matching badges to attendees? Like, are the names on the pre-mailed badges already printed on the badges, or do they just have a blank space for people to write their names as in past years? Reason I ask is, if the names were printed or there were some other method of identifying which badge belongs to which person, it might be possible for someone at each door to have a list of names that reported badges stolen, and then stop those people and verify via ID that the person is who their badge says they are. Again, it's probably a long shot, but I hate to see people do this kind of crap and get away with it.
I'm hoping the exact same thing. Maybe not names, even, but some sort of individualized barcode on the back of each and every badge? I really hope they can help this person out