actually the Parashu of India was a double sided axe used for war(it also came with a spike for thrusting, and came in single sided mode as well)
Woodsmen were called into war as well in the middle ages(read about lithuania vs teutonic knights sometimes) and they would be forced to use whatever they had available(which could be yes 2handed double sided axes)
Same with anyone classified as a viking, arms procurement was much less streamlined back in the day, don't think for a second everyone had the exact same weapon at all, hell even in the 1800's the position of Colonel was basically the guy who armed everyone, so every other Colonel had different arms/calibers generally until later
I imagine viking raiders were armed with a variety of one handed/2 handed axes, 2 handed truncheons/mauls(think studded war club/mallets), rarely any swords till much later
it seems like everyone thinks the dark and middle ages were a time of great national unity and organization, they weren't at all, the most civilized nation with the most central procurement process was the Byzantine Empire(Remnants of the Roman Empire) who were famous for 2handed axe use and loved Double sided axes as a symbol of power, I don't doubt some Varangian guards 2hand axe's may have been of the double sided variety especially if they were guarding the emperor (more for status than for use)