We are advertising a free event which people can sign up for online.
People are registering themselves more than once for the event so we are getting duplicate registrations.
If we use the back end to try to add a person to an event that they are already registered for, the system does not allow it. - That's fine.
We would like to make it so people cannot register for an event they are already registered for .
Why does the online registration allow this to happen ?