I for one question whether or not the Tuvok and Neelix who were brought back out of Tuvix were actually the same beings as the originals. I think it's more accurate to call them identical copies.
You can say the same thing about every character that ever went through the transporter. Since the characters don't bother wondering whether they're "original" or "copies" after beaming around daily, then we should assume the question isn't meaningful to them. Why would it be different for Neelix and Tuvok after emerging from Tuvix?