Schedule A Section 1b duplicate entry for state. How do I correct

That is most likely coming from your Sales Tax entries.   You can edit your sales tax information in TurboTax which will update that information.    Use the search box to search for sales tax then use the Jump to sales tax link to be taken to that section.   Click through those screen and you can remove states or edit dates if needed.  

We need to know where you actually lived (not your state of residency) and your total sales tax rate. The total rate could include both state and local rates.

Moved within the Same State
If you moved within your state and each location has a different local sales tax rate, select the same state for each location. Also enter the dates you lived in each location and the total state and local sales tax rate for those locations.

Moved to a Different State
If you moved to a different state, enter each state, the dates you resided there, and the total state and local sales tax rates.

Sales Tax Rate Changed During the Year
Enter the same location twice, once for each sales tax rate charged. Make sure to enter the dates you paid each rate.