The earlier Tales short where Gin and Dooku go to that exploited planet because they abducted some senator’s son is where Dooku began falling to the dark side.
Remember, the clone troopers took a decade to grow and train; and that it was Dooku as Tyranus that recruited Fett; and TPM and AoTC were also a decade apart.
The conflict with “only two there are” and maul and dooku both apparently being apprentices is the result of shitty writing. (Though it’s also possible Dooku-as-Tyranus wasn’t Darth Tyranus as yet and rather just a “useful” asset.)