I saw that when you click again on the confirmation link this message appears:
"Thank you for confirming your subscription to our newsletters. The newsletters you are subscribed to are listed below:
We already received your confirmation previously."
But I can see any newsletter !
In italian translation I saw that:
"We already received your confirmation previously."
is not wrote and to modify it you must add this at line 45 into italian.inc
$strAlreadyConfirmed = ‘Abbiamo già ricevuto la sua conferma in precedenza.’;