Does the feat Deepsight limit the creature's darkvision range to 120 ft. even if the creature has one or more ways to increase its darkvision beyond this range?
Your senses are especially keen in the utter darkness.
Prerequisites: Darkvision 60 feet.
Benefit: Your darkvision has a range of 120 feet.
Normal: Darkvision normally extends 60 or 90 feet.
There's no mention of the feat in the FAQ.
Things to consider
A fetchling nightblade's level 3 class feature nighteye grants him a +30 ft. increase to his darkvision range. Further, the character could wear gloom sight goggles, which increase his natural darkvision from 60 ft. to 90 ft. at the price of light sensitivity. This would be darkvision 120 ft. without the feat Deepsight, but would it be darkvision 180 ft. with the feat Deepsight?
Also, although I don't expect the character to meet the prerequisites of the feat Aspect of the Beast (night senses), he could eventually wear a cat's eye crown (18,000 gp; 1 lb.) for maybe another +60 ft. to the range of his darkvision.