Same IP, several session in 1 hour

Hello,

Here a screenshot of my "problem"
https://docs.google.com/file/d/0B8MedeG43r27LXhVeHFaMDlkV28/edit

As you can see above, Clicky records several sessions of one IP in less of one hour : how is possible ?

What about the count of Unique Visitors ?

Thank you for some help or explaination.

Christophe