The Roth IRA and Roth 457(b) are completely independent. Contributions to one do not affect the amount that you are eligible to contribute to the other.
The contributions to the Roth 457(b) are already reported with code EE in box 12 of your W-2. Enter this only in box 12 of TurboTax's W-2 form, nowhere else in TurboTax. A 457(b) is not an IRA. Go back and remove this amount from where you reported your Roth IRA contribution.
