Both feature a crime-solving duo with supporting characters.
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FL "dies" and comes back in another girl's face/body. FL is a strong, intelligent, and clever character who takes revenge upon those who wronged her. The ML is a good fighter with the FL his weak spot. Both are historical setting and part of the plot revolves around a plague outbreak with the FL attempting to find a cure.

While different in plot and tone, both feature a FL who ends up in another girl's body and lives under her identity with her family. The ML has a secret, darker identity than the persona he seems to be. Both are short length dramas.

FL transmigrates to another girl's body and assumes her identity.
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FL finds herself in an arranged marriage with the ML that turns into genuine love. The ML hides his true identity/personality behind a different persona (pretending to be a eunuch vs. pretending to be unintelligent).

Both feature arranged marriages turning into love and a scheming brother trying to destroy the ML.
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FL finds herself unexpectently married to the ML in an arranged marriage. She is not the person she appears/is pretending to be. The marriage ends up turning into true love.

Both feature arranged marriage turning into genuine devoted love in a historical setting. ML is strong and skilled at martial arts (although he's hiding it in TOGYNS), FL is intelligent and clever.

ML has secret, secondary identity while pretending to be a different sort of personality (weak, playboy). In both, he unexpectently "acquires" the FL (as a wife vs. a maid) and falls in love with her.

FL finds herself forced to marry ML. ML is bullied by his family and FL defends him, causing him to fall in love with her. ML pretends to be weak, while hiding a secret identity.

Both are short, sweet dramas in which the mains are childhood frenemies to romance, and the ML ends up falling for the FL first.

Frenemies to romance relationship between the mains. FL likes another boy first. ML falls for her long before she falls for him.