Redding expander/decapper die

I just found a used Redding die.  Curious it is a decapper AND expander die.  It appears the expander plug could be changed to other calibres.  The present plug expanding diametre is .450
Seems strange there would be a normal operation to size and not decap before using this die. 
A commercial roll sizing operation maybe.
Anyone run across this before?

This was the norm back in the 1960s. Size then expand then prime,etc...

Yes, the sizing/decapper dies came out when progressives entered the market.
Why the progressives weren't designed for the dies available beats me.
Before the late 70s, single stage presses operated with:
size
expand/flare case mouth/deprime
often, prime on downstroke
charge case, with bench-mounted powder measure
seat bullet
crimp with seating bullet or in separate step.
Also, sizing dies were steel and all cases had to lubricated before sizing.
So, I bought new carbide sizing dies and removed the decapper pin from my expander dies.
As soon as case-activated powder measures came out, I went that way too. Found, with the powder measure on the press, that it was real easy to forget to charge the case...