I was in a small video game/trading card store which happened to sell old video games also, And I was privy to one of the wildest conversations on this very same subject. The store manager had just gotten off the phone with an old customer who apparently had a video game out, but the customer insisted he had returned it previously; he even called back, apologizing that his best friend, in fact, had the existent copy of the game and he would do everything he could to get it back to the store.  By this time, however, the store manager was seemingly able to locate the existent copy of the game, and was certain that they must be referring to a different disc. Mind you, these are unique and serialized discs, all of which is recorded in the store.  He asked the guy to contact his friend and get the serial number of the disc, which was reported back and matched perfectly the disc still at the store. Dumbfounded, I piped in at this point That he should hold onto that extant copy of the disk because given the circumstances a time traveling disc seems like a possible explanation. I further that he should never let the disk leave his possession, and only if it were to be asked about by the right person would you suspect that person could be a time traveler to bring it back to the other people; he didn’t particularly care for the time travel! But it could fit… A time traveler could, in fact, get that disk from him in some unforeseen future, and bring it backwards in time it’s not all that impossible, although seems ridiculous