The problem is two-fold. Using either It's Deductible or Step-By-Step in addition to a manual entry at Line 16 of Schedule A does indeed duplicate the deduction. The problem is that TurboTax has not been updated so that disaster relief donations flow to the "100% limit" column on the "Charity Contributions Summary" form. There are two workarounds depending on the situation:
1. If your return is not subject to the 50% limit on charitable deductions, then enter the donation in the usual way and DO NOT use Line 16 of Schedule A.
2. If your return is subject to the 50% limit on charitable deductions, then enter the total at Line 16 of Schedule A and DO NOT enter the donation using It's Deductible or Step-By-Step.
