I thought it was you that has commented much on French voice actors her before...isn't "Martinet" French?
And by virtue of him voicing different characters, they would have different voices, so it's not necessarily evident that they would be by the same person if they are versatile enough. (Like Optimus Prime and Ironhide from Transformers being voice by Peter Cullen, and he's had conversations with himself.) Though yes, sometimes you can tell when it's the same voice actor if you hear enough of their work. I recognize Rob Paulsen's voice, for instance, which was funny in that TMNT episode a couple weeks ago (which seemed way too similar plot-wise to the direct-to-video movie Turtles Forever a few years back, in that the current Turtles meet their 1987 animated counterparts and briefly, their 1984 original comic versions) where Rob Paulsen voiced both the 1987 Raphael and the 2012 Donatello, and there was even a joke about that.
Besides voicing Mario and Luigi, Charles Martinet also voices Wario, Waluigi, and all their variations (Dr. Mario, Metal Mario, Paper Mario, Baby Mario, Mini-Mario toys, Shadow Mario, Dr. Luigi, Paper Luigi, Dream Luigi, Baby Luigi, Baby Wario, etc.), Toadsworth, the male Piantas from Super Mario Sunshine and onwards, all the bosses in Super Mario Advance, pretty much everybody in Super Punch-Out!!, so yeah, he's been in a lot of stuff.
