+ The Prophecy of the Chosen One is one which occurred around the Battle of Ruusan rather than a particularly old prophecy. It specifically refers to the destruction of the Baneite Sith. + Yoda's "Always two there are" isn't actually a deep insight into the nature of the Banite Sith or the Rule of Two. He just lucked out because if there's a Dark Side Master/Sith Lord then obviously he has a master somewhere. + There's actually been a couple of dozen Sith cults and a half-dozen Dark Side societies at any given time in galactic history. There's no end of wannabe Dark Lords of the Sith, most of them who don't even have force powers, the Jedi deal with. Yoda and Mace have both defeated many of them. The issue in TPM is Qui Gon Jinn means "the real deal." + The reason Count Dooku was chosen was Palpatine covering his anyx. For 2/3rds of the Clone Wars, they had the Jedi believing Dooku (a known Sith historian) was Darth Maul's master. Dooku being old enough, corrupted to the Dark Side, a master lightsaber duelist, and convenient as a scapegoat so the Sith didn't come back from the dead. + Mace and Yoda had figured out one of the Senate was a Sith Lord by the end and were closing in but it was too late. Their primary suspect had been Mas Amedda or Sate Pestage.