Kyle.
It is common practice for a casino to buy two sets of higher denomination chips. The 2nd one is put in play when they feel there is some hanky panky going on.
I have seen the back up rack put on when the house had a losing streak. Same as changing a deck of cards or the keno balls after a big win.

I am not sure if one of yours was a back up rack ot just two different sets of chips.