Running 24v and 12v Solar in parallel???

I don't understand the question. Each controller with its own array does its own thing and they add their amps until the lower voltage charger loses its overhead. This will be after they do whatever is next once they both reach set Vabs of 14.8v at the same time.

You might have to arrange settings to keep the voltages similar after that so they keep adding their amps depending on charging profiles.