There's a case to be made in arguing that Tom Riker really is just an accident and has no claim on the William Riker persona. The accident was caused by a freak interaction of a force field with a double-encased transportee. The one that got through was William Riker; the one that was reflected back to the planet was just an accident, a freak, unpredictable, unreproducible occurrence that shouldn't be considered a person anymore than a mirror image should be considered a person, and should have all the same rights any mirror image possesses.
So you're really arguing that because someone is different than everyone else, they have no fundamental rights to be alive, to have an identity and personal freedoms? It doesn't matter if he was born out of a womb, in a testtube or a transporter accident. Once he's alive, he's a person. May as well say he's less of a person because of the color of his skin.