I have most recently had the fun of trying to hook-up a distributor to fire two plugs at once on a RAJO BB Overhead Valve Kit. (Yes, it is one Mark Chaffin's overhead kits).
One of the popular ways to do this is to adapt a Datsun 200 SX cap and rotor (twin spark plug 4-cylinder from the mid-1980's) to a Bosch 009 (air cooled VW)distributor.
Here is a picture of the Datsun Distributor cap:
I apologize for the poor resolution on the inscriptions around the cap. They read: I1 E1, I2 E2,..., etc. Meaning Intake 1, Exhaust 1, Intake 2, Exhaust 2, etc. This how you hook up the spark plug wires on the Datsun. Intake and Exhaust referring to the intake and exhaust sides of the engine.
Well, the firing order for the Model T as we all know is:
1 2 4 3 1 2 4 3 1 2 4 3 1...
For the Datsun it is:
1 3 4 2 1 3 4 2 1 3 4 2 1...
Notice that they are reversed. If you read the firing order for the Datsun backwards, it is the same as the Model T.
Well, by golly! The rotor rotation in the Datsun is the reverse of the Model T.
Isn't that convenient. It means that you can use the Datsun directions on the cap to hook up the Model T.
Once in a while good things happen!
I used to have a Datsun 200SX and a Nissan hardbody pickup, both had that dual system. As I recall, the plugs on one side of the system were a slightly different heat range than the other side.
Based on plug readings after operating your system for a while, you might want to consider doing the same to get even plug color side-to-side.