"This is the same man."
'C'est l'homme même' is wrong because if même is used after the noun it means 'very', not 'same'.
In English, "very" can mean the same thing as "same". For instance:
"Do you know the rock that fell from the sky?" "Yes." "Well, this is that very rock!"
You don't see it often. In fact, people often say, "very same", but "very" can stand alone. In French, "même" is used many ways to inidicate that the noun in question is that very same noun in another part of the sentence (i.e. lui-même indicates oneself). Perhaps you think of "very" in terms of "much in degree" (very angry), in which case the French translation is "tres". Do some research for yourself, though, because I might be wrong.
From reading about.com, placing même in front of the noun means same as Duo is using it here.
Placing it after the noun, as I did in a heart trashing move, turns même into something like an extension of the noun. If I understand this notion correctly it would work something like this. If you were the host of a large group tasked with introducing the next speaker, at the end of your introduction you might say ...."And now ...This the man himself/ C'est le homme même.
Check out http://french.about.com/od/vocabulary/a/meme.htm to form your own opinion.