Some that I’ve come up with/had suggested to me:
[name_f]Rosalie[/name_f] [name_f]Estelle[/name_f] and [name_f]Vanessa[/name_f] [name_f]Lucille[/name_f] “Sallie and Annie”, 7 letters with a matching stretchy -ie nicknames derived from the middle of the name that have double letter, 7 letter [name_u]French[/name_u] middles with -lle endings and similar meanings of “star” and “light”.
[name_f]Ursulina[/name_f] and [name_f]Lysandra[/name_f] “Ursa and Lyra”, 8 letters, both dramatic and unusual, matching 4 letter constellation related nicknames.
[name_f]Juliet[/name_f] and [name_f]Elaine[/name_f] “Jet and Lane”, 6 letter classic feminine, short nicknames with the same unisex rock and roll vibe, I also like the visual similarities with the l, i, and e in the same order.
[name_f]Dorothy[/name_f] and [name_f]Rosemary[/name_f] “Dottie and Rosie”, long vintage -y names with matchy -ie nicknames.
[name_u]Arthur[/name_u] and [name_f]Ursula[/name_f], six letter bear related names with the same strong R and U sounds.
[name_m]Felix[/name_m] and [name_f]Eliza[/name_f], 5 letters, visually similar with the similar starting letter, li follwed by a pointy unusual letter, none of the letters having tails below the line.
[name_m]Hugo[/name_m] and [name_f]Lucy[/name_f], also visually similar, 4 letters, first letter with right angles, U as the 2nd letter, a letter with a tail and a round letter at the end.