TragicMonkey
Poisoned Waffles
I don't think anyone claimed that two beings are one.
But you still don't fully realize the implication there. BOTH are equally copies of the original Riker that was transported. (Who in turn was a copy of a copy of a copy of a copy.) Yet nobody has any problem treating one of them as the "real" Riker.
The other Riker isn't UNREAL. That's the point. Killing the copy is still murder even though you have "a" Riker left afterward.