I like to upload (through a query) everyone I invited to an event. So they are already in the module as "Registrants "Not Registered" but "invited".  Once the person actually registers via the OLX form, I get the opportunity to Link it to the proper constituent.  Then as I process the OLX transaction, I end up with a duplicate in the event.  I could turn on the setting to disallow duplicate registrants.  However, that means I have to delete the invite before I download the OLX transaction.  

I think it would be better if you could link to the constituent but then further link to their Invite in the event prior to processing the OLX transaction.  Instead of creating a duplicate, it would simply update the participant info to "Registered" with a date.  

The other option would be to disallow duplicate registrants, however, don't simply error out when it notices the dup (forcing you to manually delete the dup record), but rather simply prompt to update the dup with the participant info to "Registered" with a date.