This was my thinking as well when I purchased by dual regulator setup.
Reg-1 has a 4 way manifold attached to serve & carb all at the same psi.
Reg-2 will be set up to serve Soda or other "utility" uses (High psi Force Carb, pushing liquids around, etc.) without having to mess with the pressure dialed in for Reg-1
Beer is like porn. You can buy it, but it's more fun to make your own.