Thanks for working on this one Leon.
I have seen quiet a few like this and assumed they are used this way...one on top and I had never thought they may be like this of storage purposes ...a way to have a big one and a smaller one that fit easy in the cupboard..and I don't know..it is the only thing left that I dont know..when I know how they are used I will know everything
But they would make nice collectibles and some maybe these I think are hand made...so interesting.
Alex