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The impression I have is that the clerk-magistrate can change the fine, but not the specific infraction (turn a 26 mph over offense into 11 mph over, in this case).
In my case that is important because Geico is my insurer. Geico allows for one <20 mph over-the-limit infraction in the previous three years without a surcharge. But I've been found responsible for 26 mph over, even though the clerk-magistrate seemed to agree that that wasn't really what had happened.