This question originated from a recent action taken by the Highway Patrol in Brazil to catch speeders who slow down only when close to static speed radars and then speed up again. They wanted to catch speeders by placing one extra portable speed radar close (a few kilometers apart) to the other.
Besides catching speeders on the second radar what eventually happened is that some speeders received 2 speeding tickets (1 from the static radar and 1 from the portable one) and that's the point of my question: if you are driving above the limit and keep that speed for a long distance, is that 1 violation of the law or 2? Getting 2 tickets for 1 law violation might be considered a double punishment? If the idea of getting 2 tickets is OK, at which point ended the first speeding and started the second?
I specifically mentioned Brazil in my question, but this question is wide enough to be applied in other countries. Those answers are welcome too.