When I enter the Policy # on my 1095-A form that was provided to me on that form I receive the message that the Policy Number is a duplicate Policy Number

You should first go back to your 1095-A entries and make sure that you haven't accidentally entered 2 forms.  To go back to 1095-A section:

1. Open your return
2. Go to 1095-A
3. If you have entered more than 2 forms, they will be listed, and you can delete one of them by pressing on the trash can next to the forms

If you only have one, and continue having the problem, you should delete it and re-enter it.  

Please reach out again if your problem continues.