Results in group

[sitionweb]

It a while I'm noting this stuff:

try to search for paris in google, this is the serp: http://www.google.it/search?hl=it&rl...nG=Cerca&meta=

As you can see, paris.org is both 3rd and 4th. Indeed, if you, at the end of the url, add &num=6 or &num=7 and so on, you'll see only the first 6 results, then 7 and so on...

This is useful to understand in which position the "grouped" result is on the serp. In this case is 8th:
http://www.google.it/search?hl=it&rl...ca&meta=&num=7
is not in the serp any more.

My doubt is: why google present results "grouped", such as is happened for that key i've searched for?

Hope to have been clear...