That would be line 26d of TurboTax's 1099-R Summary.
The result implies that you have entered the $3,000 PSO exclusion twice, during the entry of two different Forms 1099-R. You are only allowed a total of $3,000 of PSO exclusion among all of your Form 1099-R entries, and only those from retirement plans provided by the PSO employer.
If you are married filing jointly, both of you are retired public safety officers and both health insurance paid from retirement distributions, make sure that you have not allocated both spouse's Forms 1099-R to the same spouse.
