SQL Duplicate entry error in /scritps/track_visit.php

It is possible that script track_visit.php in LiveAgent subdirectory scripts would cause SQL error "Duplicate entry ... for key PRIMARY".

Even though it might appear as error, it is an expected situation and it is correctly handled in the PHP code. To speed up execution for most visitors the code attempts to insert a new record without first checking existence of identical record, and in case of failure (if such record already exists) it updates the existing record.