No, they have the same roots and are essentially different versions of the same name. They’re both lovely, but I think both sisters deserve their own special name.
If you want another C-name, how about: [name_f]Cecilia[/name_f], [name_f]Celia[/name_f], [name_f]Claudia[/name_f], [name_f]Clara[/name_f], [name_f]Cora[/name_f], [name_f]Cordelia[/name_f], [name_f]Camilla[/name_f], [name_f]Catherine[/name_f], [name_f]Cassandra[/name_f], [name_f]Cadence[/name_f], [name_f]Christine[/name_f]
Other names with a similar vintage-class feel to [name_f]Charlotte[/name_f]: [name_f]Josephine[/name_f], [name_f]Alice[/name_f], [name_f]Tess[/name_f]/[name_f]Tessa[/name_f], [name_f]Marie[/name_f]/[name_f]Mary[/name_f], [name_f]Amy[/name_f], [name_f]Amelia[/name_f], [name_f]Margot[/name_f]/[name_f]Margaret[/name_f], [name_f]Emily[/name_f], [name_f]Lucy[/name_f], [name_f]Philippa[/name_f], [name_f]Lettice[/name_f]/[name_f]Leticia[/name_f], [name_f]Gwendolyn[/name_f], [name_f]Gabrielle[/name_f], [name_f]Georgia[/name_f], [name_f]Helena[/name_f], [name_f]Eliza[/name_f]/[name_f]Elizabeth[/name_f], [name_f]Molly[/name_f], [name_f]Laura[/name_f], [name_f]Willa[/name_f], [name_f]Lydia[/name_f], [name_f]Victoria[/name_f], [name_f]Beatrice[/name_f], [name_f]Bridget[/name_f], [name_f]Diana[/name_f], [name_f]Phoebe[/name_f], [name_f]Lavender[/name_f], [name_f]Lucy[/name_f], [name_f]Clementine[/name_f], [name_f]Mercy[/name_f], [name_f]Nina[/name_f], [name_f]Rose[/name_f]/[name_f]Rosalind[/name_f], [name_u]Evelyn[/name_u], [name_f]Flora[/name_f], [name_f]Frances[/name_f], [name_f]Maeve[/name_f], [name_f]Mabel[/name_f], [name_f]Elaine[/name_f], [name_f]Yvette[/name_f], [name_f]Renee[/name_f], [name_f]Marguerite[/name_f], [name_f]Grace[/name_f], [name_f]Arabella[/name_f], [name_f]Bernadette[/name_f], [name_f]Isla[/name_f], [name_f]Isabeau[/name_f], [name_f]Theresa[/name_f]/[name_f]Therese[/name_f], [name_f]Jessica[/name_f], [name_f]Genevieve[/name_f], [name_f]Juliet[/name_f]