No I disagree with Xizor. I always thought that the Clone Wars happened the way I said earlier. Palpatine has to get the Senate to back his plan for the Empire, and a cloned Impirial army. The best way to do that would be to pose a threat to the Republic ie Mandlore Clones. Palpatine wouldn't take the risk of creating his Imperial army only to have it defeated by the Republic. So he has to control everything. Doing it the way I said would be perfect for him. He would be slowly destroying the Republic and the Jedi and taking control of everything while they would have no idea because they are too busy fighting the Mandalore Clones. He creates havoc in the Republic and all the time his new Empire is waiting to take over.
I've now changed my mind. Palpatine doesn't need to have two clone armies as he already controls both sides. If he is in control of the Mandalore and he is also in control of 10,000 Jedi then he could easily set the Jedi up to be killed.