It's not an optical illusion and it appears to be a legit story. A Millbury woman owns a healthy cat that just happens to have two faces.
The cat has two mouths, two noses and two working eyes. A third eye in the middle is not functional. Marty named her cat “Frank and Louie” so each face would have a name. Only one mouth, the one on the cat’s right side — or Frank’s side — is connected to an esophagus, so Frank gets all the food.
I think its kinda cute.