Event: multiple registrations allowed even though allow multiple box is NOT checked

Two issues actually, Allow multiple registrations from the same email address? button is not checked, yet the user can sign up additional participants. Also, ACLs restrict access by not displaying an access button, but an information screen is displayed "It looks like you are already registered for this event. If you want to change your registration, or you feel that you've gotten this message in error, please contact the site administrator. You can also register another participant." even though the multiple registration box is not checked.