The King's Affection

The story is set during the Joseon Dynasty, at a time when twins were considered an ominous sign. As a result, when the Crown Princess Consort gives birth to twins, an order is sent to kill the daughter. To save her, she is secretly sent out of the palace.
A few years later, the twin daughter Dam Yi returns to the palace to work as a maid. When the male twin, Lee Hwi, loses his life through a case of mistaken identity, their mother, having recognised her daughter as court maid Dam Yi, persuades her to take Lee Hwi's place. Although she distances herself from everybody, Dam Yi starts developing feelings for Jung Ji Woon, her original first love and later teacher who comes from a noble family.
(Source: Wikipedia)
~~ Adapted from the manhwa "Yeonmo" (연모) by Lee So Young (이소영).