Aha, found it. This carburetor is also on Webhead’s Chromer chainsaw. Knew I had seen that before. I was about to go nuts looking all over the net and on the forum. Now I can go to bed
Looks to me that they tried to make the old carb more modern and added a diaphragm fuel pump. I'd say that line coming out by the motor mount would be the pulse port for the pump, and the other line feeding fuel from the tank.