I could be wrong, but I believe the problem sets at the end of the lessons in the CC contain questions from PTs 17-35 only. The drill packs that have questions from PTs 1-16 should be questions that you've never seen before. Again, I could be wrong.
The blind review group: https://7sage.com/discussion/#/discussion/11817/september-study-group-pt-64-sunday-july-16-7p-edt-6p-cst-4p-pst-harry-potter-poll
We get together on Sunday and talk about the questions that posed a challenge.