[sudo-users] What are sudo timestamps used for?

[Leroy Tennison]

In working on a system I came across /var/lib/sudo. The man pages indicate that timestamps are kept there and the discussion is under security. On the system in question there are several files for my ID spanning a 15 month time frame. What are they used for? Why do multiple exist? I guess the real question is whether there is any usefulness in them, can i discern anything significant from their existance, dates or content?