The events of the movie is recorded in the official databank of Star Wars. I think that is enough for it to be considered canon.
Spoiler:
BUT Anakin did not exactly defeat Dooku. He fled if I recall properly. Dooku had the upper hand whenever he was putting effort into it.
Anakin fled to rescue Ahsoka from General Grievous's Magnaguards. Prior to that, he disarmed Dooku and had him cornered. Though I will note two things in all fairness: a.) Dooku wasn't worried (probably because he knew Skywalker would rush off for his apprentice) and b.) during the duel, the lightsaber skills seemed to be equal, but Dooku did knock Anakin on his ass big-time with the Force.