My home of record is in Oklahoma, but I'm a full-time student and part-time Army National Guard member in KS. Am I required to add both states for tax purposes?

[DanielV01]

No.  Since you are active-duty, all active duty income is taxable in Oklahoma only.  If Kansas was mistakenly withheld, you would file a Kansas nonresident return to get back any mistaken Kansas withholdings.  But you are not otherwise taxed there.  

You would only need to file a Kansas return if you have non-active duty income derived from Kansas.  But if all your income is active duty, and you did not have any Kansas tax withheld, you do not need to file that return.