Why is Turbo Tax reflecting an amount in box 8 that is not reflected on my w-2?

Your W-2 should be reported just as it is on paper. 

If you imported it, you may want to delete it and manually type it in. 

To Delete a Form  using TurboTax Online:
Select Tax Tools on the left side-bar
Select Tools from that drop-down
Select “Delete a form” on the TOOLS CENTER screen
Select the W-2, delete and confirm

Be sure to re-enter it.