[M. Nordlund]

I was looking for images of french arms and armor around the turn of the 14th to 15th century and found a surprisingly large number of images of axes that could be interpreted as having two vertical spikes or knobs on the "back" of the head. So I was wondering was that a thing, do the images even depict the same thing and what is it?
Is it two spikes or knobs or a depiction of the four pronged heads common on later pollaxes or something else?
Are there any extant examples or other images depicting these kinds of axes?

I have never encountered axes that seem to fit the style before and I found them a little intriguing and decided to turn to you guys for any input.

Sources of the pictures in the image in maybe the same order as they appear in the image:
http://manuscriptminiatures.com/5848/23055/
http://manuscriptminiatures.com/4310/13894/
http://manuscriptminiatures.com/4310/13895/
http://manuscriptminiatures.com/4296/9119/
http://manuscriptminiatures.com/4310/13881/
http://manuscriptminiatures.com/4310/13882/
http://manuscriptminiatures.com/4144/7427/
http://manuscriptminiatures.com/5201/16737/
http://manuscriptminiatures.com/5198/16728/
http://manuscriptminiatures.com/5828/22686/
http://manuscriptminiatures.com/3986/10892/
http://manuscriptminiatures.com/4257/9101/

[J. Scott Moore]

I would strongly suspect that the artists are trying to accurately portray a pole axe of some type, imho, though, it should be said that i do not presume to be an expert, just an enthusiast. I did find this article to be informative however: https://myArmoury.com/feature_spot_poleaxe.html

[Victor R.]

I suspect what you're seeing is a depiction of a weapon along the lines of A&As Burgundian Pole Axe. only with the hammer prongs mounted 45 degrees to the A&A item (square to the blade rather than diamond).

This picture linked below comes from a listing presently in the marketplace for one. There are several other pictures there.

https://myArmoury.com/talk/download.php?id=64682

[Gregg Sobocinski]

I agree with the others that it's likely that you're seeing an artist's interpretation of the textured head on a hammer face.  Based on those first few images from the list you posted, I could be convinced that there might have been some axes with a double spike alternate face, but it doesn't seem practical.
 
That said, I'm fascinated to see so many depictions of long pole ax types using a hammer head WITHOUT the top spike! I have seen a few single-handed axes with smaller hammer heads on the back, but these images present a new type to me. I've always thought the Cold Steel poleaxe looked odd, but it seems like they got it right this time! They are the only ones who seem to offer this style of poleaxe in the repro market, which is odd, since accuracy it not their priority. 

Has anyone seen such an ax-hammer combination in a museum or collection without the top spike?

[M. Nordlund]