In the car world that is known as a Tri-Y header. On the header you’ve shown, the first 2 pipes are 2x resonance pulse length and the length between the first and second collector is 1x. It makes a bunch of nice pulse resonances to build torque.
I had a set of 2x/1x tri-y headers on a Chevy race car I owned. I Y’d each bank together another 1x downstream. The total length was about 48 inches to the final Y. That combination was good for 50 Ft-lbs on a 350 CID engine over shorty (1x) headers Y’d together about 48 inches downstream.