Those are two design pad hold down "clips" "plates" that were used on the Mopar, and Ford, Kelsey Hayes, 4 piston calipers.
The big one was used on the 65-66 calipers, and the small one is used on the 67-72 calipers.
But either or, will work on all year calipers.
Don't worry about it.
Don't loose any sleep over it.
Use which ones that you want too.
They all serv the same purpose.