How does Marquez explore dualities in his story?

I cannot write your essay for you but you might consider the blurred distinction between natural and supernatural. Marquez contrasts the supernatural in the story with vivid natural details, thus conflating the supernatural and the everyday. Pelayo does not see a large difference between a natural oddity - the invasion of his house by crabs - and a supernatural one - the invasion of his house by a decrepit angel. Indeed, when Pelayo and Elisenda build their mansion, they secure it from crabs and angels alike, thus treating both as equal nuisances. Moreover, the angel's wings are described in gross, vivid detail, and when he first appears they are crippled by mud. He is described in one place as a senile vulture, in another as a 'huge decrepit hen among the fascinated chickens', and in paragraph four the crowds treat him as a 'circus animal instead of a supernatural creature.' These comments serve to blur the distinction between the natural and supernatural. Garcia Maquez may be suggesting that such a distinction is unnecessary, or that the people are simply blind to it. Whether it is a failure to impose the boundary or ignore it is a matter of interpretation - and the story, ultimately, invites interpretation more than it invites meaning.