I've always thought it was a way for Winchester to use the barrels intended for the .30-30 that turned out oversize when the drilling was complete. Instead of scrapping them they reamed them to .32 caliber and rifled them. I really don't have a clue why anyone would bring out a round almost identical to an existing one in the same bullet weight and the same rifle with the same energy level.

Ballistically there's nothing special about the .32 Winchester special.