Distributor setup

I have GT4, 10848, manufactured May 1975. It has 2 coils and 2 distributors, one for each side of the engine. I also had an 84 GTS that I believe had the same setup. Currently Bring a Trailer has GT4 10584 with 2 coils, both feeding a single distributor. When and why did Ferrari change this setup?

 

When the US version 308 needed 2 sets of points inside each distributor. 10584 has a US version engine that has the euro "single distributor" system installed (and most of the emission equipment removed). That euro "single distributor" is just about as complicated as the two US distributors -- it does only have one mechanical advance mechanism, which is a plus, but, the cap and rotor are more complicated. Also, the wire routing to the plugs is more complicated/lengthy, so on the 308i-2V (both euro and US), they stayed with a true single distributor for each bank (without a complicated cap and rotor), and that carried over to the 308QV (both euro and US).

PS Not being run in the past 10 years = it's already overbid