Why does the stihl 151 have two chokes?

[spudulike]

Two strokes are one of the simplest engines out there,  the piston and cylinder are pretty simple once the timing and durations have been designed in. Two major moving parts - not like the four stroke with valves, springs, cam shaft, cam chain/belt/gear, lubrication pump, etc etc. 

The strato doesn't really make the engine more complex, you still have a cylinder, a piston, an inlet manifold, a carb.....they just look different.

Fuel injection in to the crankcase does allow much more efficient control of the fuel input that the typical cylinder based inlet port can't and controlling the timing and duration can be electronically controlled to give more torque and power - try an old machine with reeds where the carb feeds fuel direct to the crankcase - more torque in most cases...... 

It is how Bimota went some 30 years ago but failed....an interesting story!