No, once you have entered the code DD in box 12 into the W-2 screen, you do not need to enter this amount anywhere else on the return.
Code DD in box 12 of the W-2 is the sum of your employer's contributions towards your health insurance premiums and your contributions (if any) towards your health insurance premiums.
This amount has been removed from Wages in box 1 of your W-2, and they are therefore "pre-tax".
