Yes it is illegal-different states have alternate laws. Own a salvage yard and you will find states demand a paper trail. If you own a 1969 and you have not photocopied the title from both cars you have removed and replaced VINs. Your resident lawyer that rebuilt a 69 M code former race car using panels from another 69 barracuda unless he has photocopies of both titles indicating the panels reused can be prosecuted should a later owner complain. Be very careful when you are judging someone else because I guarantee that none are”Lilly white”!!!