In this exchange, I sent a number of different photos, (almost) all done by making an overexposed enlargement onto very old, fogged paper, bleaching it, redeveloping it, reducing it, toning it, drying it, then rephotographing it and using that copy negative to make the postcards. This is an example.
There was no double exposure - but I did sabbatier the print while developing it (not much, though). In the original negative, there was almost no detail in the sky and everything looked pretty well-defined. I wanted to get a harsh type of contrast and a lith-look. I wanted it to not look particularly real.