Underground Chemist + Alchemist?

[Andy Ferguson]

Do there respective int to damage abilities stack?

They are written very similar, but have different names.

[Splendor]

I would say yes. Just like sneak attack from different classes stack.

[Zwordsman]

I think you would get int to damage twice if using a splash weapon.

two different abilities that give you extra damage

[Andy Ferguson]

I guess I am a little worried about there being confusion cause the abilities have much of the same wording.

[Richard McGuffin]

I believe there is a Faq somewhere that states you cannot add the same ability modifier more than once.

Sorry It's not a FAQ but it is a rather credible scource.

Creative Director James Jacobs:
Can you add the same ability modifier twice to the same ability? No.
http://paizo.com/threads/rzs2l7ns&page=385?Ask-James-Jacobs-ALL-your-Qu estions-Here#19247
And again at:
http://paizo.com/threads/rzs2l7ns&page=386?Ask-James-Jacobs-ALL-your-Qu estions-Here#19274
And finally:
http://paizo.com/threads/rzs2l7ns&page=444?Ask-James-Jacobs-ALL-your-Qu estions-Here#22160