Too similar for siblings, in my opinion.
[name_f][/name_f]That said, I know siblings like this. I know a [name_m]Victor[/name_m] & [name_f]Victoria[/name_f], an [name_f]Ivy[/name_f] & [name_m]Ivan[/name_m], and an [name_m]Everett[/name_m] & [name_f]Evelyn[/name_f]. If these names seem fine to you, go for [name_m]Emrys[/name_m] & [name_f]Ember[/name_f]. If they make you uncomfortable, probably best to find an alternative.