This can be answered by this logic. We've always been focusing on two specific people - Bethie and SP. But it can be any two from our eight.

Therefore, we have to multiply the probability of two players choosing the same team (let's use the 1 in 16 million number for now) with the number of combinations of 2 players out of a group of 8 players (i.e. we use the "choose" function - 8 choose 2).

If we were a bigger group, say out of 5000, the probability of any two players choosing the same exact team will be a lot bigger since now we multiply the same probability as before (1 in 16 million) with 5000 choose 2 (which is much bigger than 8 choose 2).