Generally this happens if you live in one state and work in another. So it is probably your case, unless you lived in MO for part of the year and KS for part of the year.
To to the taxes to easiest, you
First do the Federal Return,
2nd do the non-resident state (as this state will tax you only on what you earned in that state).
Last do the resident return, this will tax you on all your income (double tax) and then you will get a credit for taxes paid to the other state.