*****TWO-FACED SPOILERS!****** 1972’s blaxploitation horror-comedy “The Thing With Two Heads” followed the release of earlier double-headed transplant/monster movies, including 1959’s “The Manster,” and 1971’s “The Incredible 2-Headed Transplant.” “Thing…” was created at the 1970s height of the blaxploitation-horror subgenre, which yielded such cult classics as the “Blacula” movies (1972/1973), 1973’s “Blackenstein,” and 1974’s “Abby” (a knockoff…