Bonus stacking - Same type of bonus, but multiple descriptors for effect?

[quibblemuch]

QUESTION: If you have two X-type save bonuses against two different effects, do those bonuses stack?

EXAMPLE: The deathtouched trait gives you a +2 trait bonus against mind-affecting effects. The courageous trait gives you a +2 trait bonus against fear effects. If you are the target of a mind-affecting fear effect, is the total bonus to the Will save +2 or +4?

MY THOUGHT: At first glance, I'd say the bonus is +2, the rule against same-type bonuses superseding the fact that they are trait bonuses against different effects that happen to come from the same source. But I'm not completely sure.

Thoughts?

[James Risner]

+2 because they don’t stack.
It doesn’t matter why the bonus was added, just that it’s the same type.