A character just acquired a Serpent Belt which gives a +4 bonus vs all poisons.
This belt’s wearer gains a +4 bonus to all poisons.
The same character also has a Comfort's Cloak which gives a
+4 competence bonus to saves against disease, energy drain, effects that cause fatigue or exhaustion, and poisons.
Because of the wording, I assume the bonuses stack as one is a straight bonus, and the other is a competence bonus, for a total of +8 vs poisons. However I could very well be wrong, so I wanted to ask for help.