I have made another trip to my grandfather's shed and I found some more tools that I am very interested to have and use (like the adze I got!). I have been watching enough episodes of The Woodwright's Shop to know that I found a scratcher gauge.
Also with it was what appeared to be a pair of mortise gauges. One is pictured below. Good guess is that it is homemade so there's nothing to look up. I say "appeared" because all the mortise gauges I have seen both scratchers are on the same post with one of the "nails" being adjustable.
My problem with this is that: If you were to use this for a mortise you would have lines protruding the mortise area which could be seen.
Am I wrong about what this is? If I am right would you just use this like a regular mortise gauge?