Well, I guess the next logical question would be: Have any true bicephalic squids ever been found, especially ones of the Giant variety? And if any bicephalic specimens of smaller species have been found, were they living?
Bicephaly (or dicephaly? -- not sure) may be rare, but there have apparently been numerous recorded cases in a variety of species: snakes, turtles, sheep, cows, pigs, etc., and many of these "dual individuals" have survived and thrived just fine, thank you. In a most stunning human case, 12-year-old conjoined twins Abigail and Brittany Hensel share an entire body and have no trouble attending school, bicycling, swimming, diving, etc. (And no, they do not wish to be called a "two-headed girl"!)
[FYI, if Discovery Channel happens to run it again, there is a remarkable and deeply inspiring TV special about these bright and beautiful little girls, called JOINED FOR LIFE, which should not be missed by anyone who doubts the strength of the human spirit in adversity.]
Getting back to the topic at hand -- have there ever been any true bicephalic squid?