The reproduction voltage regulators have points that stick, keeping the alternator charging circuit on line feeding the ignition even though the key is off.
Normally, turning the key off kills voltage to the VR alternator field circuit coil, and then the engine shuts off.
1912 Model T Ford touring Salmon (ugh!)
1913 Model T Ford Touring original Black paint
1915 Model T Ford Roadster Black
1915 Model T Ford touring Black of course!
1967 Cougar GT 390 Cardinal Red / Black
1968 Cougar GTE 427 Augusta Green / Saddle
http://www.supermotors.net/vehicles/registry/15029/50071-2