Registration issue

Scenario that has occurred, with changed names.

Contact  John Smith jsmith@acme.com.  John Smith  registered for the event using the email address jsmith@ac.com.  He misspelled the email address.  We received a confirmation email of his registration, but his name does not appear on the attendee roster report.  When we go to his record, there is not registration activity.  A second John Smith record has not been created.  Where is this registration?  Things are not right and we are unsure to fix when this happens again.

thanks