![2girls black_background black_bodysuit black_eyes black_hair bodysuit boots cross-laced_footwear earrings fate/grand_order fate_(series) faton fingerless_gloves gloves highres hoop_earrings ishtar_(fate)_(all) jewelry katana knee_boots lace-up_boots long_legs midriff mirror_twins multicolored_hair multiple_girls red_eyes red_hair space_ishtar_(fate) sword two-tone_hair weapon yellow_footwear rating:s score:18 post #3723474](/cdn_image/preview/7b/79/7b79f0bd021e32e108da0acea0b99d03.jpg)
mirror twins
Describing two characters that look, are dressed, stand mirrorically identical to each other.
Despite the name, the tag doesn't refer family relation of characters, but their mere visual connection in terms of look, clothes or pose which is either same or similar just mirrorically inverted.
If characters are actual twins add also appropriate tag. Same if both characters are actually dual persona of same character.
If picture simply contains just one character twice in mirrorically identical pose, then use symmetry tag.