To me, it appears to be an old Organic Engines Troika tandem except that it has been modified to have all of the drivetrain on the right side. Look at this photo here:
https://cimg9.ibsrv.net/gimg/bikefor...92a2ac9927.jpg
You can see the "wing" shape on the cruciform, as well as the two smaller tubes running down the top and all of the vertical supports between the upper and lower tubes.