These names are taken from Nameberry's "Berry Taste," where they ask you which of two similar names you like better. Some of the boy ones I came up with because I was given more girls than boys.
Bella or Stella
Louise or Eloise
Sophie or Sophia
Victoria or Veronica
Sarah or Zara
Willa or Willow
Seraphina or Serena
Annora or Nora
Tess or Nell
Evelyn or Ava
Elle or Ella
Maren or Marin
Clara or Claire
Adelaide or Adeline
Dahlia or Iris
Lenore or Leora
Thomas or Timothy
Brian or Byron
Miles or Milo
Blake or Blair
Maddox or Pax
Benjamin or Benedict
Griffin or Gavin
Finlay or Finn
Reese or Rhys
Elijah or Elliot
Reid or Reed
Caspar or Caspian
William or Liam
Jacob or Jacoby
Lucas or Luke
Nathan or Nathaniel