In my experience, if you're looking to buy the original, you'd best take responsibility yourself for determining which you're getting. (The picture above is great reference). The average store or online SA is likely just going to tell you it's Chanel Pour Monsieur. If you press them on the "concentree", they'll just say it's the same formula but more concentrated which isn't exactly true.
The possibility is also real that they won't even notice/pay attention to the small "concentree" written on box and bottle.
Opinions vary on the juice itself. I've seen some in here who tried both that say the differences are minimal. Others think the original is the gold standard of men's frags and the concentree version is a dreadful flanker.
There does seem to pretty widespread agreement though that the original, wonderful though it may be, has no legs and is very fleeting. I have the concentree version and it's a nice enough scent to me. But it too a little light in the longevity department.