Taxable by both states:
By PA because PA residents are subject to PA income tax on all income, regardless of its source.
By WV because WV taxes non-residents on royalty payments derived from in-state natural resources.
You may claim a credit on your PA tax return for the taxes paid to WV on that income, so in effect you won't be double-taxed. Be sure to prepare your state returns as described by @MayaD.
Yes. You would file a non-resident West Virginia State Income tax return to report Royalty Income.
The income is also reported on your resident PA return, though you may qualify for a resident credit for tax paid to other states on income earned outside of Pennsylvania.
Pennsylvania residents are subject to Pennsylvania personal income tax on all Pennsylvania taxable income classes, both Pennsylvania and non-Pennsylvania source income. PA.gov
To ensure accurate calculations, always complete the non-resident return first.
Taxable by both states:
By PA because PA residents are subject to PA income tax on all income, regardless of its source.
By WV because WV taxes non-residents on royalty payments derived from in-state natural resources.
You may claim a credit on your PA tax return for the taxes paid to WV on that income, so in effect you won't be double-taxed. Be sure to prepare your state returns as described by @MayaD.