I would suggest you delete your W-2 entries and re-enter them using this method to delete them:
1. Choose the Tax Tools option on your left menu bar
2. Choose Tools
3. Choose the Delete a form option under Other Helpful links
4. Delete all W-2 forms in the list
Once you have deleted the W-2 forms, re-enter them manually and make sure you only make one entry for box 17, State Income Tax.