Duplicity is often associated with deceitfulness or two-facedness, and there are several words that can be used as synonyms for it. One such word is deception which refers to intentionally deceiving or misleading someone. Another synonym is deceit, which is characterized by dishonesty or fraudulence. Malice is also a good substitute word, implying a desire to harm or cause injury, while guile suggests cunning or slyness. Hypocrisy is another synonym for duplicity, which implies insincerity and a lack of authenticity. Whatever word is used to convey the meaning of duplicity, it all points to the same thing - deceitfulness, dishonesty, and a lack of trustworthiness.