I gave this book, "Is Data Human? The Metaphysics of Star Trek", to my friend Chris shortly before he died from complications of muscular dystrophy.  I don't know whether he had time to read it.

It ponders a lot of the philosophical conundrums inspired by Star Trek tech, such as androids and transporters.  Our friend Tom B. says that he's chill with the idea of being scanned, destroyed, and re-created as an identical copy.  But what if the process goes awry?  This happens to Commander Will Riker, who winds up with a "twin" eventually named Thomas.  Is the "duplicate" going to be just as sanguine about being destroyed to balance the equations?  What if it's unclear which copy is "excess"?

If you played Rock-Paper-Scissors with yourself to solve this problem, would you keep tying endlessly, or are you already different enough to make different choices?  If you're already different, are you really exact duplicates?

this thread is the definitive exploration of the subject:
CM Adams 3/24edited