Okay, but the division of the Dakota Territory into two states was done, at least in part, to game the system and secure more seats for the 1870s Republican par

Okay, but the division of the Dakota Territory into two states was done, at least in part, to game the system and secure more seats for the 1870s Republican party. It's not just a matter of "well, there turned out to be two states, and so they just happen to get two sets of representatives and senators" - the causal arrow points in the other direction.