Documented solution for detection of users connecting with multiple screen names?

Question

Say that I have a site where I want to detect users using multiple screen names, based on their connection data. I would want to detect them even if they are not using the multiple screen names simultaneously, but rather sequentially. Do you know of any documented method for doing this?

Answer 1

User agent string and IP address combined can give you a pretty good (but not perfect) indication of unique users. You can also try storing the usernames they connect as in a cookie or using DOM storage.