>> jay dillon: this is some of the biggest news ever. >> wertheim: jay dillon is a rare book dealer in jersey. he ranks the columbus letter as one of the most important documents ever printed. >> dillon: this was one of the first bestsellers. it is probably the first contemporary account of anything to be published across europe. >> wertheim: today, only about 30 copies of this columbus letter still exist. >> dillon: each one is now worth something in the low seven figures. >> wertheim: more than a million dollars? >> dillon: more than a million, but probably less than four or five million. >> wertheim: it was while researching columbus letters on his home computer, back in 2011, that jay dillon first noticed something amiss. the national library of catalonia in barcelona had posted photos of their columbus letter online. what struck dillon as odd: it looked exactly like a columbus letter that he had seen for sale a year earlier, right down to the same smudge marks in the margins. and you're telling yourself what at this point? >> dillon: i'm telling myself that one of them has to be a