Problem after full copy system disc with duplicate content
 

This night i made a complete bootable backup with the non registered versione of superduper.
My system drive is 80gb and has 33gb of data, now the data is 66gb , as like all the content has been duplicated, but i can't find that duplicated content.
A find command on terminal says me the bigger file on hard drive is 2gb so there isn't a big 33gb file as i originally thought.
How can I solve this problem ?
Thanks in advance.

Did you make the backup onto an external drive?

yes of course

well I have solved repristining the system disc with the image of the full backup, and I will buy the complete versione of superduper as soon as possibile,