The 'Leica II' is in fact a Zorki. Re-engraved, painted black, and all brass parts left the factory as chromed parts and were de-chromed by the forgers. Sometimes the lens elements are put back in wrong or the shutter springs are in wrong, so you can't even use the camera.
They often were forged from the early 1990s on to sell at auctions, flea markets, antiques fairs etc and be passed off there as 'valuable Leica' with either a 'small defect' or in 'pristine condition'. Forging continues to this day though.
The Leica I looks legit. See the difference in paint sheen, brass sheen, brassing itself, and vulcanite pattern with the forged Leica II. Evan apart from engravings quality and the cameras specific Leica features and dimensions.
Side by side with a forged Leica I, the difference would be soooooo obvious, you'd cry with laughter!