Exactly its typing that matters and the untyped abilities unless stated otherwise stack even if the abilities draw from the same source for a #. That example is easier as Deflection + untyped.
If the abilities give "+stat mod to ac" then its not untyped... that itself is a typed bonus. Similar to dex mod to AC. So its either typed or not and ive always understood monks to be untyped class bonus. Not sure why PF which copied 3.5s monk wording 100% would try to change the typing of the bonus... with out changing its wording.