“I received two W-2 forms from the place I work for. In each of them the box 16 has the same wage. But in box 15, there are different states in each of them and box 17 has different state income tax withheld as well. Is this same income being taxed on both states?”---->I guess you may have worked in two different states for the same employer. Or, if you worked in one of those states( I mean you worked in one state as a non-resident of the state) while living in the other, as a full year resident of the state, both states would tax the same income; in this case, you can claim the tax paid to the other state where you paid your tax as a nonresident alien on your state tax return as a full year resident.