Do not enter the SIMPLE IRA contributions anywhere under Deductions & Credits. A SIMPLE IRA contribution with respect to self-employment is entered under Wages & Income -> Business Items -> Business Deductions and Credits -> Self-employed retirement plans.
If the SIMPLE IRA contribution was made through an employer that provides a W-2, enter the amount with code S in box 12 of the W-2 only in box 12 of TurboTax's W-2 form, nowhere else in TurboTax,