The would be amazing sibling if they weren’t the same name, [name_m]Just[/name_m] like [name_f]Margot[/name_f] [name_f]Pearl[/name_f] would be the cutest combo! What about:
[name_f][/name_f][name_f]Margot[/name_f] and [name_f]Florence[/name_f]
[name_f][/name_f][name_f]Margot[/name_f] and [name_f]Olive[/name_f]
[name_f][/name_f][name_f]Margot[/name_f] and [name_f]Imogen[/name_f]
[name_f][/name_f][name_f]Margot[/name_f] and [name_m]Frankie[/name_m]
[name_f]Greta[/name_f] and [name_f]Louisa[/name_f]
[name_f][/name_f][name_f]Greta[/name_f] and [name_f]Ingrid[/name_f]
[name_f][/name_f][name_f]Greta[/name_f] and [name_f]Imogen[/name_f]
[name_f][/name_f][name_f]Greta[/name_f] and [name_f]Phoebe[/name_f]
(though honestly, it would probably only be the namenerds who know that they are the same, your average person probably wouldn’t care/wouldn’t know)