625 ILCS 5/3-505

Whenever the owner of a vehicle properly registered in another State transfers his interest thereto, Illinois evidence of proper registration in such other State, that is an Illinois Reciprocity Permit or a Prorate Decal, shall expire and the owner shall remove the same from such vehicle and forward the same to the Secretary of State. The owner may, however, instead have such Illinois evidence of proper registration in another State assigned to another vehicle also properly registered in another State, upon payment of the fees required by law and subject to the rules and regulations of the Secretary.