This ad was on FB Marketplace. The seller says that this is a 1948 Duel Professional. Stamped on the input jack plate, there seems to be a D that looks like THE ‘D’. Price was crazy good for this, if it was legit.
I saw that Dual Professional on Reverb or somewhere. It's an early one and in pretty good shape but way overpriced...you can find similar examples for around $1,500 give or take. I have no idea what the 'D' means or if it has any significance. There was a later, Walnut colored one at the Dallas Guitar show in immaculate condition with case and legs priced at $1,500, probably could have offered $1,000 late in the show and walked away with it.
The second picture is a Fender Stringmaster...those have blendable single coil pickups and are longer scale than the Dual Pro.