In the first chapter of David Copperfield, David’s aunt Betsy Trotwood asks Mrs. Copperfield what she calls her servant girl so that she can summon her. Names are on her mind as she asks this, since they are discussing what David’s name is to be. Mrs. Copperfield replies that the girl is called Peggotty, which scandalizes Aunt Betsy. She exclaims,
Do you mean to say, child, that any human being has gone into a Christian church, and got herself named Peggotty?
Mrs. Copperfield explains that her husband always used to call Peggotty by her surname because the girl’s Christian name, Clara, was the same as Mrs. Copperfield’s own. The reader soon sees for him or herself how much confusion this would cause, since Mrs. Copperfield’s new husband, Edward Murdstone, always calls her Clara, and it would scarcely do to have a servant girl with the same name.
Besides this reasoning, Dickens is famous for his aptronyms (sometimes spelled "aptonyms")—names that perfectly fit and announce to the reader the characters of those who bear them. The Murdstones are an excellent example of this, with the first syllable suggesting violent death and the last indicating something cold and hard. Similar instances abound in every one of Dickens’s novels: Cheeryble, Gradgrind, Dedlock, Verisopht, and so forth. “Peggotty,” with its rustic charm and suggestion of the sea (a sailor’s peg-leg), is far more apposite for the loyal old retainer than the classical-sounding “Clara.”