Antonio, This is really awesome.
"Oh wow this makes plenty sense Antonio, I really have to get your book. From your text above, I'm really thinking this sure sounds like the method could still be Double. The reason I state this and I could be wrong because I haven't read your book. Is in this double sheet metal method the precious metal wasn't mixed with the base medal but would lie separately on the surface. They would use alloyed gold for this process, but we are talking silver of course. With Silver, a much stronger thicker layer of tombac or silver was used. This could explain the X-ray anomaly and the two layer band as you call it. During the production of double sheet metal, the sheet surfaces would be scraped smooth and flat, then are placed on top of each other, heated in a furnace and welded together under hydraulic presses at very high pressure. Nothing is perfect, so maybe this is where you see the lifting between layers or between the sheet metal. Thank you for listening to me babble lol. Can't wait to get your book. Best!
