If box 2a is the same as box 1 or is the box 1 amount minus the box 5 amount, then that indicates that the 401(k) was directly rolled into a Roth IRA which is a taxable event, and not into a Traditional IRA which would be non-taxable and have a 0 (zero) in box 2a.
Since the 401(k) and Traditional IRA's are before-tax money, then a before-tax account is converted to an after tax account (Roth), the tax must be paid at the time of the conversion.
If that is what you did, then in the TurboTax interview, you would answer "yes" to the 2nd Roth question where it asks if the money was rolled into a Roth IRA. Enter any amount in box 5 when it asks for your contributions and that will not be taxable.
You are not paying twice, since the money will be tax free when withdrawn for the Roth in the future.
If that is NOT what was done, and the money is NOT currently in a Roth IRA then either the issuing trusted made an error on the 1099-R and needs to correct it, of the receiving bank put the money into the wrong type of account.
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**