Why do Speeding Tickets happen in Pairs?

There have been tons of discussion around "Flashy Car Colors leading to tickets", but do speeding tickets happen in pairs (read: within a week) ? Well based on my experience in PA and in WA, and some of my friends here at work (who shall be unnamed for once on my blog), The the answer to this is Yes.

This is counter-intuitive to logic. One would argue that after the first infraction you would go slower for a while and the chances of the 2nd ticket closer to the first would be a lower probability event.

Apparently not. I am lost on explanation for this observation though. Are there any other theories out there?