I'm not shitting you, I have an OC named Akiko and she looks almost exactly the same, only her eyes are golden and her hair is silver/any other colour ever because she loves dying it.. She's got the same attitude too.. Great minds think alike!
Using Photoshop: duplicate the layer of her. On the lower layer of her now, press Ctrl+T (Transform), right click, choose Flip Vertical. Move it down to her feet. Then lower the opacity (and adjust the colors a bit if needed). That's how I did it. C: