I am trying to enter information for a state tax refund from a 1099g and I keep getting an error that the information from my state is already entered

I had the same issue , could not enter Calif State Refund for 2016 which I received in 2017, TT feedback on red text  "you already have entered data for this State/Locality".  I was able to enter my CA State Refund as follows:  For State, I entered Arizona instead of CA, then I was able to enter the State Refund, I then went to Forms and corrected the State info on the Federal Carryover Worksheet.  

I spent 1 hour on the phone with TT support, they reommended deleting the Federal Carryover Worksheet but I did not want to re-enter all the data again.  It is a bug that TT needs to fix