Duplicates on the Web

There's a huge amount of Web pages – but how many of them are duplicates?
We keep on hearing about billions of pages - but how many of them are unique?

Suddenly I realized that QTsaver's presence on the web has grown considerably.
Looking at the pages more closely I saw that some of the links contained duplicate contents.
Eventually I understood that this system of RSS FEEDS is bringing the message to more people than I expected. For example, my letter to the editor of NewForge appeared simultaneously on the following sites
http://japan.linux.com/
http://www.linux-magazin.ro/
Lampgroup
http://digitalmagi.com/
cissrv3.uwsp.edu/wdmd/resources.php
feeds2read.net/rssview-75.html

These sites change their whole content in a few hours, so that the post was there for only a short while, but since the Web remembers everything these duplicates will go on living for ever in the CASHE…