... Wait hol up, when did we do that? It's been a while but I don't remember Maul at all... [spoiler]not included in the DLC[/spoiler]
On the return to Raxas Prime (sp?). Proxy ambushes you, and fights you as all the other bosses in the game. Once you get him to half health, he turns into Darth Maul. So it was just a fake, which is why “Darth Maul” is in quotes.
Your droid goes all hologram and shit and loads the darth maul file.