KEY WEST -- They are touted as being tongue-in-cheek but look authentic: navy blue and red ``passports'' embossed with a ``Conch Republic'' crest -- complete with photo, blank official-looking pages for immigration stamps, personal identification information and expiration dates. Now federal investigators are trying to find out whether Mohamed Atta, one of the men believed to be a key player in last month's terrorist attacks against the United States, added one of these novelties to his collection of travel documents. After discovering that a man named Mohamed Atta applied for and likely received one of the passports in September 2000, ...