Glide Speed (both propellers feathered) for best range - 100 KIAS
Glide Speed (both propellers feathered) for best endurance - 77 KIAS
I've been to Initial and Recurrent at Flight Safety, Toronto and have never seen Glide Speed for both engines out...although I could have used them for the last recurrent.
Not doubting the info, as your posting on the airplane was correct, but where are these officially posted? The AFM?