So that’s why weekend warriors spending an hour at the cafe mid ride are all so lean 
It is very interesting though, generally speak twice daily workouts seem to be frowned upon or seen as a novelty with perhaps some benefits but should only be toyed with periodically.
From an intensity POV I get that, but if you’re doing polarised then this could be great news. No time to download and read the whole PDF but I’m assuming both workouts were endurance? Or high intensity followed by lower intensity?