Dooku seemed overwhelmed by Anddeddus holocron which implies to me that he would be disappointed by the real thing, overall it's not improbable for either Sith to earn a victory, but at the same time, someone has to win meaning it will inevitably become improbable for both to win, as only one of them can win in a given timeline. That is unless one of them is resurrected, and as we saw, Andeddu was able to resurrect himself.
Depending on the battle conditions for a suitable victory, both or neither Sith could win, as Dooku would outright kill Andeddu but then die of natural causes, and then Andeddu would resurrect meaning, Dooku could win the initial battle but lose in the overall war, or Dooku could not win because Andeddu comes back to life but Andeddu could also not win because Dooku died out of combat to natural causes, meaning that neither wins and the battle is a stalemate.