Well, partly stumped. The White Powder (WP) Wonder was made around the last turn of the century. As far as I know, all were single shot. The "white powder" refers to smokeless powder. For shotguns, this was usually a cream colored (white) powder that looked a little like large grain soap powder. It was very light in weight for its bulk. It was made by DuPont to be loaded with the same dipper as an equivalent load of black powder.
The WP Wonder was not expensive, under $5.00, I seem to remember, but it had a drilled solid barrel rather than the Damascus barrels put on the "better" shotguns. So in this case, the cheaper gun was actually better.
They were interesting in their day, but have virtually no collector value and probably should not be fired. Today's loads are too powerful for those old guns, even if they were made for the smokeless powder of 1900.
I don't know who made them, maybe Harley can help with more info.
Jim