Yes I looked at this thing too and suggest that it was supposed to be a mandocello.
I have no idea why any builder would put "tenor guitar" on the headstock -- goofy. #So I think Mike is obviously correct it was added later.
But the nut is just the right width for a mandocello -- the scale length is a tad shy but you could fix that with the right strings.
Interesting insturment -- maybe someone set out to make an 8-string tenor -- ala a 12 string standard guitar but that seems unlikely
Obviously owned by a women? (the rose after Emmy Lou Harris on the front).
It seems worth more than is being bid right now --in my opinion.
Due to current budgetary restrictions the light at the end of the tunnel has been turned off -- sorry about the inconvenience.