Hi again 2U2.
Did you win the dizzy?
Generally the idea is to allow for more coil saturation by allowing one set of points to close then the other a little later. The first set then opens and the second set stays closed for a bit longer before opening to allow the coil to build up a higher charge.
At least that is the theory. Some say dual points make a difference some say not. There was even an old trick of turning off one set of points in 3rd and 4th to retard the timing. Ted Eaton mentioned that in a post on another forum. I had never heard of that.
I put a Mallory dual point conversion in my first 56 I had in HS in 1964. I don't know if it made a difference but it was cheap and was the cool thing to do.
Here is a link to an explanation from a MGA (4 cylinder) forum but it touches on some other things also.
Mallory Dual Points distributor, how it works, and Why Dual?
Jim