I know I cant be taxed on the same income by two different states, but (even after filling in the tax credit) its still saying I owe $655 pa, and $755 de?

Actually,  you can be taxed on the same income in two states if you work in one state and live in the other. 

But if you are paying tax on the same income in two states, you can claim a credit for taxes paid to another state.

You will need to prepare your nonresident state return first, then as you are working through the state you live in, you can claim the credit in the credit section of your state return.

For further information, please click here.