Ground feathering on PA 34
After landing on a PA 34, on low RPM taxiing, one engine stopped and feathered. I restarted, it unfeathered rotating above 1000 and on low RPM (800) it gradually stopped and feathered again.
I restarted, it unfeathered and I pulled mixture lever cut off. The engine stopped and after some seconds I saw the dead propeller feathers to rotate slowly to the feathered position.
What is going on?