Since the power levers really acted as "rpm command" levers in flight, if you reduced power too quickly, instead of slowing down you would get a sudden slight increase in speed as the props coarsened in an effort to reduce the rpm.
I'll go along with that. Training a new Pilot Officer on the VIP HS748 at Canberra around 1968. In those days it was traditional service training to conduct instrument take offs from brakes release keeping straight on the main compass. The instructor in the RH seat offered minor corrections as he looked outside.
On rotation the QFI rapidly pulled back on throttle to simulate engine failure (bloody silly thing to do but we did bloody silly things in those days). The pilot locked on to the compass reacted immediately by applying rudder to prevent yaw etc. But as explained in the earlier post the "failed" engine momentarily coarsened its prop giving an apparent increase in power which the pilot picked up and so he applied rudder in the wrong direction. He was fast - I'll give him that and very quickly the 748 rolled under the influence of the now pulled back throttle and wrong rudder input. The lesson learned from that close shave was to in future slowly pull back the throttle to simulate engine failure and at a safe height.