If it is pulling in the full amount to PA go back to the federal and change the state code to "XX", then you should be able to make the adjustment for the amount allocable to the state. 

If this still doesn't give you the result you are looking for without an override, go back to federal again and make two separate dividend entries (as if you had two separate 1099s).  

Enter the amount of federal less Pennsylvania in one and use state code XX, then enter the difference and code that one to PA in the state box.