Originally Posted by fantasyfan
They are silly sounding names used by Dickens to satirize certain types of vacuous silly aristocrats he feels are stupid. He uses the same techique in Hard Times, though there the names are symbolic of social positions and/or ethical attitudes. e.g. "Bounderby" is a vicious, horrible capitalist who is a "Bounder"--an untrustwothy villain and cheat.
Most of Dickens' characters fill that description to many character types. In this case the difference is Coodle and Doodle are imaginary to the story. ..thanks fantasyfan.