Originally the ignition and door locks were keyed the same. However, if your ignition key does not work in either door, it must have been replaced at some time. It is also possible that one of the door locks has been replaced at some time. If you are lucky, you can have a key made for the passenger door that will also work in the drivers door. If not, then you could simply lock the drivers door from the inside and use the keyed lock on the passenger side to lock the car. Yes, it is inconvenient, but if, like many of us, you use the car infrequently then it is a possible solution. You can also buy a new lock with a key from places like Roberts or Bernbaum.
Dave