Duet of Shadows

Both are Republican Era dramas with two female leads (who eventually move in together) and have plots involving mysteries. Sun Yi Han plays one of the main leads in both.

Both are mini dramas and have two FLs trying to solve mysterious murders and cases. One is Republican Era setting, the other modern day.

They're both mystery dramas directed by Li Yutong that feature two female leads (a detective and a medical examiner) with imho nice chemistry. The actress Li Yuan is also in both (as a main character in The Evidence Tells and as a guest character in Duet of Shadows).