Yes, it's unusual; it's a particular set of markings sometimes called a "Chimera Cat," quite rare. Scientists believe that it is possible that such cats at first were going to become two kittens, but the egg never divided, so you have the colour characteristics of two cats in one.
"Venus" is the most famous (picture below) with the most extreme markings, and even different colour eyes:
Yes, it's unusual; it's a particular set of markings sometimes called a "Chimera Cat," quite rare. Scientists believe that it is possible that such cats at first were going to become two kittens, but the egg never divided, so you have the colour characteristics of two cats in one.
"Venus" is the most famous (picture below) with the most extreme markings, and even different colour eyes: