Unusual dulcimer bridge

I was gifted with the very old traditional dulcimer. it has  a very unusual bridge on it I've never seen one like it. The bass string is a little higher and angled to the tail piece the middle and melody are cut facing the nut end. Anyone know anything about it? I'm thinking it was for noter ,drone the bass not supposed to be fretted or just something the builder came up with for his own use Anyone else have one like it?