If both Form 1099-R represent the same distribution, then check the forms carefully to be sure that one of them is not marked 'corrected'. There is usually a box at the top of the form that could be checked if it was corrected by the issuer.
If you do have a corrected form, enter only that one into your return.
**Say "Thanks" by clicking the thumb icon in a post
**Mark the post that answers your question by clicking on "Mark as Best Answer"