Topic awaiting preservation: Avoiding non-unique cached visitors to be counted

Hi. I have installed in my webpage a script, by www.proxy2.de, that counts the daily stats of the page. It's a very neat and useful script. You can see it working at the maker's page or at my page (www.viol.net/mohaa).
But, I guess there is a problem with it and since the support for the script is non-existent (unless you pay), I'm trying to fix it by myself.
The problem is: the script is supposed to count only unique visitors to the site. But, analysing the table of IP addresses (you should click the "Visitors" link to open this table), I can see clearly that there are some IP that, although different, they must come from the same visitor. Here are some examples (header is Time, IP Address and Host name):

20:26 205.188.209.51 cache-dl12.proxy.aol.com
20:25 205.188.208.172 cache-dh08.proxy.aol.com
20:14 205.188.208.107 cache-df07.proxy.aol.com
20:14 205.188.208.69 cache-dc01.proxy.aol.com
20:05 205.188.209.173 cache-dr09.proxy.aol.com
20:04 205.188.208.37 cache-db01.proxy.aol.com
20:04 205.188.208.102 cache-df02.proxy.aol.com
19:57 205.188.208.10 cache-da06.proxy.aol.com
19:57 205.188.208.7 cache-da03.proxy.aol.com
19:52 205.188.208.42 cache-db06.proxy.aol.com
19:52 205.188.208.42 cache-db06.proxy.aol.com

For me, this must be just one guy, browsing around the site, from 19:52 to 20:26, and, for some reason (cacheing), for each page he visits, he has a different IP address, so the counter counts him too many times.
Note that all my pages has a code to count, based on the IP. So, if the guy has a unique IP, no matter how many pages he visits, he'll be counted just once (unless he stays browsing for more than two hours in a row). But, if the guy has this "modifying" IP, he'll be counted more than once.
My idea is to analyse the IP address and, if, during a certain period of time (30 min., for instance), the first three sets of three numbers of the IP address are the same, to count just once, so, from the examples shown above, from 19:52 until 20:26, this guy would be counted twice: once for 205.188.208 and once more for 205.188.209, and not eleven times.
My question: am I right to conclude these movements of IP addresses come from the same guy?
If so, is there a better way to count him just once, rather than analysing the first three sets of the IP address?
Thanks.

After searching and reading Internet sites, I found a good script that seems to deal with the situation described.
Here: http://www.TSinter.net/
It's the TScounter script. It seems that using only IP addresses is not that safe for counting unique visitors. Cookies can help although there is no definitive solution.

i dont think this is the same user, probably just some strange AOL proxy software that hits your site.
but i could be wrong...