That's interesting because I can't seem to find the exact CPU that these laptops ship with anywhere on the page. The ThinkWiki page shows that there are Core Duo (not 2!) and Core Solo variants of this laptop that exist as well.
If I'm not mistaken, thinkwiki gets their info from the thinkpad service manuals. (I have one too). There are a billion configurations of every laptop, most of which you'll never see because they were restricted to one region or market (or govt or edu). Some of them probably never even made it into production, but they exist as a row in a database.