The Fire Emblem Warriors Twitter has just revealed some gameplay of female Robin.
— 「ファイアーエムブレム無双」公式 (@FireEmblemMusou) August 16, 2017
Until we see more of both Robins in action, we can’t be fully sure that they are 100% clones. That said, since Female Robin is confirmed to be only playable outside of story mode, it’s very likely she’s just a skin with a bit more detail.
It’s entirely possible that male Corrin will receive this same treatment–being a skin of the already announced female Corrin. However beyond these two Avatars, I highly doubt we’ll have any other “clone” characters like this.