When creating the tickets and adding the Requestors information to the tickets, the comparison is done with the Sender Email Address and that of the existing Requestors Email addresses. If there is a match, only then the Requestor is populated on the ticket.
Check you server for this log and see what the "Requestor Email" value is being captured. If there is a mismatch in what is being captured by the BR then you need to fix the BR.
if there is a match then Track-It! must be storing the email addresses wrong in the DB. This will need further investigation.
Or possibly update the email address for that user in the system.