Ok so the tax disc might fail a walk by check, but until then if the cloned car was the correct make, model and plate, and the genuine car is still taxed and insured, it will pass a fixed roadside ANPR check, where the vehicle is not stopped up until the point where it is found to be a clone.
If the genuine car is in Luton, and the cloned one in Leeds, it could take months for it to be spotted, and the genuine owner may never know, until the speeding tickets come through.