The Dup Check option is necessary for patient creation. Why? Because without any Dup Check option in any field of the Create New Patient screen, the new_search_popup.php screen appears empty and it is not possible to create a patient.
This should not happen. If Dup Check is really necessary, an error message should alert about that issue.
So if you completely disable Dup Check you can’t create a patient?
Exactly. You see a missing page error.