The amount you use from the PA return is the PA AGI for income taxed in both places.
You have to be sure to use the PA Tax liability (the amount of PA taxes paid in on W2 as well as any additional tax due to PA to cover the PA tax liability) on that amount of PA income.
The thing is that if you are getting a refund of some of the PA taxes paid to PA then that cannot be used as tax credit, only the amount that PA is keeping.
