California Penal Code 496 defines Receiving Stolen Property as purchasing or otherwise taking possession of items you know to be stolen. As a general rule under California laws for receiving stolen property, this means someone else actually stole the goods and you subsequently received them. The original thief received stolen goods too when he stole them but he can't be charged with both the original theft and receiving stolen property. Otherwise Penal Code 496 could tag along with practically any theft charge.
However, California law allows one exception. This happens when a person steals an automobile and is later caught driving it. Under the case of People v Garza (35 Cal. 4th 866), this person can be charged with both Receiving Stolen Property and California automobile theft under Vehicle Code 10851.
The key is that for the state to add the PC 496 charge, it must be “post-theft driving.” This means the person wasn't simply driving the car away from the place it was stolen (otherwise this would be part of the theft itself). But the courts have not clarified how much time must pass for the post-theft exception to apply. If the thief is caught driving the car several days later, it clearly would. But if just a few minutes, or an hour, or a few hours have passed, the law is not so clear.