This latest update (7.3.1) concerns Blocked Times.
Previously the allow-double-booking option would override all time checks relating to the practitioner and any resources.
Now, however, the allow double-booking option no longer relates to blocked times. An appointment cannot be made that overlaps a blocked time for a user.
This change has been made as a request from one of our users and we agree that it makes sense. Thanks for your input.
Please email support@diarybook.com if you have any queries about this release.