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Don`t polish !! If you do that will cost you at least part of whatever it is worth !! This is one time that brass is better left alone !! I would list it in one lot and just tell what you know about it and that the knob is the same as was on the hotel doors !! As to it being different from some of the known hardware,, I would imagine that the higher priced rooms had the more ornate back plates !! Smaller, less expensive rooms were a bit less fancy !! Hotels often have different grades of rooms !!