Double-sided coin variant

Hello, while sorting this coin in my collection I came across a double-sided variant that I cannot find in the catalog here. After further research I came across the fact on the internet that there are 2 variants of the double-sided coin. Could someone please help me where to classify my coins? Thank you

https://herbison.com/someoldcoins.org/saur/1/0183.htm

https://herbison.com/someoldcoins.org/saur/1/0184.htm

There are many similar coins with two sides

https://en.numista.com/catalogue/index.php?e=bohemia_royal_mint&r=&st=all&cat=y&im1=&im2=&ru=&ie=&ca=3&no=&v=1&cu=3395&dn=&a=&dg=1300-1500&i=&b=&m=1&f=&t=&t2=&w=&mt=&u=&g=&c=&wi=&sw=

I'm suspicious that only one is one sided and all the others are two sided.

If I was going to research further I would see what references are available. The most common for these coins on Numista is 
Beschreibung der Sammlung böhmischer Münzen und Medaillen
Numista code  Don
Authors  Eduard Fiala, Max Donebauer

That is very old, so it might be available as a PDF.

And I also look at MA Shop listings for similar coins, they usually list newer books as a catalogue reference, although I have not found a list of the abbreviations they use. I have in the past ask on https://www.numismatikforum.de/ which book corresponds to an abbreviations. At least you are in Europe, so you might be able to find some of the book in university libraries not too far away. 

As oops correctly pointed out, coins featuring both faces appear to be equally common. I have searched the available bibliography to the best of my ability, but it isn't listed.

Note on physical specs: it is very light, weighing 0.22g with a 13.7mm diameter.