odds and straps

So today I bought 2 straps off the clapboard prizewall and both are the exact same. I was like that seemed crazy, and also not the first time it had happened. So I start doing the Math and boy apparently I just have astronomically bad luck or....

This is going to get deep here so hold on. What makes up a belt, well 4 things Era, Sex, Class, and Bonus.

Era is 1 in 7 (Not IOW or HOF)

M/F is 1 in 2

class is 1 in 6

bonus is 1 in 10 (I can't click to see if there were more options than that as I bought the 2 straps)

That is 840 combinations (7*2*6*10)

Now that is assuming there is no weighting happening giving different types higher chances. Just straight-up odds which is what it should be.

Now here is where it gets really crazy. if there are 840 combinations to get the exact same belt combination 2 times in a row is 840*840 or 1 in 705,600. 839 other combinations could have come up on belt 2. Now for it to happen multiple times when I get 2 belts is even crazier odds which seems like there is an issue not just astronomical odds.

So is something SUS with the belts when you get multiple at the same time that the odds don't re-roll? Or is my math of combinations off, which it logically checks out, and I ran it past my structural engineer to make sure it seemed right.