If I understand correctly box 12a says DD Amount, and box 12b says DD Amount. Are the amounts the same? If so I would only enter it one time. If the amounts are different, I would add both amounts together and only report box 12a.
DD is for health insurance. Did your company switch health plans in the middle of the year by chance? That could explain why it is listed on 2 separate lines, but they should both be reported together.
**Say "Thanks" by clicking the thumb icon in a post**Mark the post that answers your question by clicking on "Mark as Best Answer"