I, probably like the rest of you, have had problems with people using your name and posting comments. This, fortunately, can be resolved. I was planning on writing my own PHP code to get this working, but someone has done this already. Therefore, I decided to use that instead. The code can be found at http://www.dagondesign.com/articles/prevent-author-impersonation-in-wordpress-comments/
For websites that show comments without being moderated first, this PHP code snippet will benefit these websites greatly. At least, I hope it does.
In any case, do not assume that the same person with the same name is writing two comments. It could be that there are two different Jane’s writing a comment. Treat all comments as if they are all from a different person and treat all the previous posts written by the same person as different people.
After looking at this website, it has lots of useful stuff. I will have to dig through and see what other goodies lie behind those links.