Assuming you were a part-year resident for New York at the beginning of the year but then moved to Pennsylvania during the year and established your domicile in Pennsylvania, you would need to allocate your dividend income based the percentage of time your resided in each state. For example, if you lived in New York for 6 months and then lived in Pennsylvania for 6 months, then you would allocate 50% of the dividends to each state. Make sure the amounts allocated to each state add to the overall total reported on your federal return.
The adjustments will be made in the state interview sections for each state. Please see this link for additional guidance to help you as you prepare part-year state returns for each state.