There may be only 3 or more duels, but there are otherways to "fight" as well.
Anakin vs. Dooku
(Anakin will become a hero in the clone wars by defeating dooku in his own ship & end the clone wars this will happen in the very begining of the movie as we all know)
Yoda vs. jedi traitor (new bad guy/girl with the two sabers)
(Yoda discovers the jedi traitor seeks him/her out & defeats the traitor)
Mace vs Anakin/Vader
(Mace sacrifices himself against Anakin/vader & a bunch of clone troopers so that Kenobi & padme & her kids can escape) *SLJ said that his fight scene he will be on the defensive.Rick said "possibly" when someone asked if he'd be dueling a Sith.
Kenobi vs Anakin
(everyone knows this Kenobie tries to save Anakin from the dark side witch doesn't go accordingly like Kenobi would of liked hehehe)
Rick McCallum said that there'd be no Yoda / Tyranus rematch.
Everyone knows that there are quite a few similarities from the Classic Trilogy to the Prequels, and the flannel one himself Lucas himself has said it...