Looks like Anakin may indeed be Vader by the time of the duel.
The Official site did a big update tonight on several key characters. There were 2 things about Anakin's that stood out. First of all they mentioned in OB-Wan's bio that he is now on the Jedi Council. They made no mention of Anakin on the Jedi council. Also they state that he becomes Vader and they make that statement before they talk about the duel. So perhaps this will be the case. I've copied Anakins Bio update (the parts pertaining to EP3) and provided a link for the rest. This is NOT hyperspace material. But interesting stuff, discuss.
http://www.starwars.com/databank/updates/news20041108.html
After a brief convalescence wherein Anakin's severed arm was replaced with a mechanical one, he accompanied Senator Amidala back to Naboo.There, at a secluded lake retreat, the two were secretly wed by a Naboo holyman in a ceremony witnessed only by C-3PO and R2-D2. It may have been the start of a new life, but it was another step to Anakin's eventual destruction.
If Anakin felt his time as a Padawan was a trying exercise in restraint, the Clone Wars would prove to be an ever greater challenge that would mold his character. Apprenticed to Obi-Wan in the thick of the fiercest fighting the Republic had faced in centuries, Anakin became a man against the backdrop of seemingly ceaseless war.
Despite Jedi platitudes about peace and patience, Anakin found the battles of the Clone Wars invigorating. He felt alive in combat, and his incredible Force abilities were further honed. It was Anakin who single-handedly transformed inevitable defeat into victory on numerous occasions. Encounters on worlds such as Cato Niemoidia and elsewhere cemented Anakin and Obi-Wan's legendary reputations. Throughout the Republic, citizens would spread tales of the two Jedi heroes -- Anakin's hologenic features and daring exploits earned him the moniker of "The Hero Without Fear." Skywalker became a celebrity of the state, despite Jedi ascetics frowning upon such accolades.
That is not to suggest the war was without its difficulties. Time and again, the Separatists pushed, and Anakin would find himself restrained by his oaths to the Jedi. He couldn't share his darker thoughts with his fellow Jedi -- the thoughts that overwhelmed him that night in the Tusken Raider village. He knew that such a path was a gateway to more power, but it also led to the dark side. The only person he felt comfortable confiding such troubles to was a friend he had since his days as a child hero on Naboo: Chancellor Palpatine.
Palpatine encouraged Anakin's talents. In many ways, Anakin felt Palpatine was the only one not asking anything from him. He was simply letting Anakin be, and appreciating him for his efforts and talents -- he wasn't imposing boundaries nor begging for aid.
Another ache for Anakin was the absence from his wife. Long weeks would stretch to months wherein Anakin would not see Padmé. As a devoted Senator, she kept a watchful eye on the war, but much of her interest on the scattered reports of the ongoing conflict was deeply personal. The five months they were apart during the Outer Rim Sieges tore at their hearts.
In the last year of the Clone Wars, Anakin and Obi-Wan were stationed in the Outer Rim when word came of a shocking development. Coruscant was under attack. The planet that held not only his beloved wife, but also his close friend the Chancellor, was in the crosshairs of the merciless General Grievous and his droid forces.
It was with a fierce determination that Obi-Wan, Anakin, and their Republic forces launched towards Coruscant, to parry the blow to the Republic's heart.
As turmoil engulfed the galaxy during the transition from Republic to Empire, Anakin fell to the dark side of the Force. Consumed by evil, Anakin abandoned his past and his humanity. He became Darth Vader, Dark Lord of the Sith, apprentice to the evil Emperor Palpatine.
Sustaining grievous injuries at the hands of his former master, Obi-Wan Kenobi, Vader required cybernetic enhancements and replacements to sustain him. His pure innocent self seemingly lost forever, Darth Vader cast a dark pall over the galaxy, as he was one of the foremost agents responsible for the elimination of the Jedi order.