Finally I got to see this engine when I was visited by Kurt that borrowed it from its owner to show me.
And indeed it was a chopped up Militor motor that someone with brute force had cut the heads of by means of a grinder. lets just hope this violent act took place many many years ago.
I have previously found that Militor was represented by Lindzen & Robsahm in Kristiania, as well as their agent in mid-Norway "Nordisk maskin & Automobil kompani. Apparently they might have sold one of those great bikes too.
There is another add from the well known company Gresvig in Kristiania offering Militaires too. Gresvig where the ones later to sell ACE motorcycles.