[drc]

There was an episode of Dr. Who, who owns a time machine, that involved multiple Mona Lisas made by a nefarious time traveling alien. Dr. Who examined the paintings, all spread out in front of him, and declared them all originals. For identification purposes, he wrote on the backs. Later in time had a hell of a time trying to convince the tour guide at the Louvre that he should be allowed to take down their Mona Lisa and look at the back.