The scumbags are also taking your VIN (Vehicle Indentification Number) posted in the lower left corner of your windshield and using that number to create an ID for the stolen car they're trying to sell. You'll never know until one of the two vehicles is sold or crashed at which time you'll have to prove your's is the correct car.
Even though it's illegal, you can put an obstruction of some sort over the ID tag so they can't read it. Just explain to the patrolman why it's there.
More things to worry about from the "End Of The World Is Near Crowd"