I wonder if the reason for two dials is so that it can be seen by two persons at the same time. We don't how big this thing is but I'm guessing about 8" long, because its hand held one would expect that a single dial version could be used in two positions saving the expense of a second dial.
Another oddity are the four 'feet', if its for checking the level between two surfaces or rails it would only need feet on the bottom, also if it was going to be used on rails then presumably it would have some lateral guides to cater for the crowned surface.
Is the height between the top and bottom feet significant. Maybe this thing is used with the plunger at the top sat between the ram and a platen of a hydraulic press.
More dimensions would be good, its not clear how this thing is assembled but there might be some clue if there is any writing on the dial mechanism. All in all though its an intriguing mystery
Ian P