So, I'm looking at Gunnery Team (upgrade) and Advanced Gunnery (objective).
Gunnery Team:
"You can attack from the same hull zone more than once per activation. That hull zone cannot target the same ship or squadron more than once during that activation. "
Advanced Gunnery:
[...]
The Second player's objective ship may perform each of its attacks from the same hull zone, and it may do so against the same target.
[...]
So, in this case, the rules on each of these cards explicitly contradict one another. My guess is that the objective card takes precedence over the upgrade card (you can fire twice at the same hull zone on the same ship), but what do you all say?