They look quite alike in the bottles but they are not dupes. Barry M's Mediterranean has a flash of pink which Impala's Sex Appeal don't have. This is due to the almost foil finish of Mediterranean. Sex Appeal is more smooth and also shows a darker shade of orange too.
Sex Appeal has a much stronger chemical smell than Mediterrean, uncomfortably strong actually, but I still prefer Sex Appeal over Mediterranean. It's more smooth and intense. If you are a big fan of orange/red douchromes you of course need both of these :)
In these pictures I've got Barry M Mediterranean on middle finger and pinkie. Impala Sex Appeal on pointer and ring finger.
Which one do you prefer?