Some good pix there P, but unfortunately no "...full report..." that I could see.
The Twin-Mustang was designed to overcome both the pilot fatigue ( by offering duty-sharing) factor
- for very long range ops & the clear obsolescence of the P-38 twin engine fighter, offering marked performance improvements.
However, it ran into post-war budget cutting/political-technical issues..
1stly, the Air Force wanted jet fighters, & no new piston jobs, ( even if early jets had their faults).
2ndly, the mandated US GM-Allison powered aircraft showed themselves as under-performing compared to the original Packard-R-R Merlin powered prototypes/early production machines.
There were several high performance twin-engine contemporaries to the P/F-82, such as the Grumman
F7F Tigercat, & the British DH Hornet, but they were both likewise too late for WW2, & overshadowed by
the new-fangled jets, so they all had their planned production numbers cut severely.
The F-82 did its duty by standing guard against the Soviet ( B-29 analogue) bomber threat from Siberia,
& saw combat - successfully, against single-engined Russian-built prop-fighters - early in the Korean conflict.