Two penalties for one offence?

[pgro]

I overlooked taxing my car, purely an oversight (first time in decades of motoring...). DVLA stung me for a clamp fine. Paid it immediately, and purchased all relevant road tax etc. Weeks later the police have decided to take a bite from the same cherry (ie me). Can the individual be punished twice for the same offence?

[New Judge]

I have not come across this before but I imagine that the first fee was an administrative charge for unclamping your car. Any subsequent fine will be for failing to tax your vehicle.