Math head here. You're running into what is called the birthday paradox. The typical way of presenting the problem is as follows: how many people need to be in a room such that the probability of two of them having the same birthday is at least 50%? The answer is 23, which is surprisingly low.

Translating this to raid: it's very unlikely that you get duplicate souls of a specific champion (which you announce in advance before popping your soulstones). But it's pretty likely that you'll get a duplicate of some champion.

I'm not saying that Plarium is definitely not cheating, but it's unlikely given that they're making money hand over fist even with fair probabilities.

Thanks for that, do take into consideration it was 2 pairs of champions which in terms of probability seems well off

Do you have a link to explain the birthday paradox.  I used to be good at math (many years ago) and would like to research it as part of the probabilities here.  

Voilà 

How did you know I took French in high school?  Merci.    lol

Thats all good math, but in real life, this whole thing becomes untrue. Because everyone likes to be the center of attention, at least once in a while, therefore, people having the same birthday tend to not be friends with each other, making it less likely to be found in the same room.

Theory debunked :P

Yeah...before entering a room, I always ask the people about their own birthday and if it is too close to my own, I chase them out.....aehm..wait...no actually I do have a friend whose birthday is the same as mine...it saved us a lot of money as we are celebrating our birthday together and we have the same group of friends...

Theory debunked...debunked..;-)

I was hoping for something along the lines of 56 million to 1 rather than ostracizing somebody at a party with the same birthday lol. Not so helpful 

This answer by Urlibu is as well put as anyone could ask for:

Translating this to raid: it's very unlikely that you get duplicate souls of a specific champion (which you announce in advance before popping your soulstones). But it's pretty likely that you'll get a duplicate of some champion. 

Basically the odds are pretty good that we'll all see a decent amount of dupes over the time we play. :)

I'm sure it is, guess I'll teach myself and share my findings as Yoda style overview comments, however accurate they are, are not hitting the spot.

Yeah, raid champs and souls really don care if there's another copy of themselves in the collection before the enter. 

Random sampling of independent events!

on the other hand, I never walk into a room without checking first if there's anyone in the room taller than me /jk

non-random sampling of dependent events.

Its really nice to always be the tallest in the room :)

Maybe this'll help:

https://www.dcode.fr/birthday-problem

Thank you that's awesome!