What would happen if the blades of a variable pitch prop did not all have the same pitch?
Never say never, but that's not a prop malfunction that I've heard of or that was ever addressed in the turboprops that I've flown.  We had various prop malfunctions, but the ways that things could fail that we considered would pretty much leave all blades in the same place.  So without claiming that it could not, ever, ever, no way no how, not in all possibility ever happen, I'll say that it's not very likely.

If you did get something like that, the vibration would probably be bad enough that you'd shut the engine down, and at that point the interesting question would be, do all the blades feather for you?  (The answer to that probably depends on what type of prop you have and what specific failure mode led to the condition in the first place, and now we're into too much speculation for any answer to be very enlightening.)