"He would still be his exact duplicate "
Ummmm no. Same DNA is not an exact duplicate, even ignoring the nurture and environment thing, there will be physiological differences. An obvious physical example to demonstrate the point, his fingerprints will be completely different, so you can just imagine all the underlying differences that in the end make him a completely different person. This is why cloning of this kind is just pointless and misunderstood as to what it actually means to clone someone.
