I looked at the lit details on some of the Schwinn made hubs and it seems they only had one washer, and probably it was their serrated lock washer. Like I mentioned earlier not one of my 60's bikes had the flat washers, just the serrated one. I'm thinking the New Departure rear hubs Schwinn had came complete from ND with the flat washers and the nuts so when the wheel was installed on the frame they just added the serrated lock washers and reinstalled the ND supplied flat washers and nut.The reason I think this is, why would you need double washers and why would Schwinn spend the extra $'s on hardware that really wasn't needed.