Your son in law should speak to his local police.
Explain the history re getting stopped.
Request they put a note linked to the ANPR data with his details and a note ,too, of the repeated stops.
Also make sure he has photo ID on him. This would then probably allow on the spot clearing up rather than custody.
Has he asked if the clone car is also a Merc of same colour/model etc?
Provided the DVLA have correct details re him as V5 named keeper the repeated stops will be annoying to say the least. It is only likely to st when they catch the offending vehicle.
Maybe he should get DVLA to issue a new reg?
Worth a try if it continues.
To get new plate you must go to a licensed supplier with V5 and photo ID. But the "benefits" of a false plate mean there is a black market.
Also plate theft is on the up.....but mainly for common run of the mill cars to enable make/colour etc to match the cars up.
One of the downsides of the increasing pressure on motorists with points/disqualification system. Desperate unscrupulous people out there cloning plates. Besides criminals trying to hide their ID.
