DURING INITIAL CLIMB PHASE OF AN EXPERIMENTAL FLT FROM MGM, AL, THE PLT RPTED THAT THE LEFT ENGINE HAD FAILED AND AN ATTEMPT WAS MADE TO FEATHER THE PROP. THE PLT RADIOED DANNELLY TOWER THAT THE ACFT WAS RETURNING TO THE ARPT. THEN THE PLT RPTED THAT THE RIGHT ENGINE LOST THRUST, HOWEVER THE RIGHT PROP WAS NOT FEATHERED BECAUSE HE WAS NOT SURE IF THE ENGINE WAS PRODUCING POWER. A GEAR-UP FORCED LANDING WAS MADE ON A 4-LANE HIGHWAY. THE ACFT ENGINES WERE FUELED WITH ALCOHOL WITH APPROVAL OF THE FAA FOR RESEARCH AND DEVELOPMENT. THREE DAYS PRIOR TO THE ACCIDENT THE ACFT EXPERIENCED POWER SURGES AND MADE A PRECAUTIONARY LANDING. NO PROBLEMS WERE FOUND AND THE FLIGHT WAS CONTINUED. INSPECTION OF THE ACFT REVEALED THE RIGHT PROP FEATHERED AND THE LEFT PROP IN LOW PITCH. THE ACFT WGT AND BAL INDICATED APPROX. 400# OVER GROSS WEIGHT. THE ENGINES WERE SUCCESSFULLY TEST RUN. THERE HAS BEEN NO DETERMINATION AS TO THE CAUSE OF THE RPTED ENGINE FAILURES.