This item turned up on eBay in 2005, with a description as follows (with the grammar tidied up for clarity):
"This is Yashica's pre-production experimental TLR camera based on the Yashica-Mat. The camera emitted two beams of lights for focus assist which is very useful for shooting under dark area (sic). As you focus, two circular light images overlap each other to form one circle. When that happens, you have the correct focus. Another difference is the lever added to the focus knob. There is a battery holder box on the back cover. All else seems to be same as Yashica-Mat. A must have for serious Yashica collector. As far as we know, this is the only one in existence in the US".
It all seems a bit technocentric and perhaps unnecessary, although perhaps it helps when taking flash pictures in very dark conditions. Though not enough to make it a saleable proposition, presumably?