Charles is obviously a family name (Charles Musgrove, Mary's husband; Charles Musgrove, Mary's son; Charles Hayter and one can presume Charles Musgrove senior, Mary's father in law). Names were often reused - Austen makes fun of it in the first chapter "all the Marys and Elizabeths".

This sounds so important! There is a family rumour/myth/tradition that Austen had intended to title this book The Elliot's, an interesting choice as this is almost chronicling the downfall of a once great family.