AFAIK, two people with the same three IP octects being two unique people would be 1 in 1 million chances so I assume I can be rest assured it's someone's bought trying to scrape my pages.

As samtregar points out that's a very bad assumption. I'm thinking of NAT'ed systems behind a firewall as well. If you had two people coming from the same university for instance there's a great potential they will the same IP address never mind the first three octets.