1.The dual pickup can be used in a race car without a start retard box. One pickup is used while cranking, then the other one takes over when you release the starter switch.
2.I use one for a fuel injection setup, where one pickup is used to send a signal to the injection computer for a tach signal, the other pickup is used for my Ignition control module for spark timing.
That distributor does not have any advance weights or vacuum advance built into it and the pickup plate is locked. It wouldn't be worth anything to you unless you are a MAD SCIENTIST, like me.
Rob