So, theoretically, you could get a deadly accuracy twice. can you choose the same combat skill? adding ten damage to anything seems pretty nice, granted expensive to go about it that way, but still nice

Can't take the same Skill twice.

The Sharpshooter Talent Tree has Deadly Accuracy twice, and the Bounty Hunter career has it once each in Assassin & Gadgeteer (two excellent in-career specs to complement each other), so I'd say it's entirely plausible (more than just theoretically possible) for a combat-oriented character to have two iterations of this talent.

As to the specific question, at the end of the rules regarding the specified talent, you'll find the text: He cannot choose the same combat skill twice. So that pretty much precludes the suggested double-dipping

I figured it was a bit too good to be true