Twofold are the reasons duplicitous is next in this series.

Duplicitous
[ doo-plis-i-tuhs, dyoo- ]
This adjective means:
- marked or characterised by deceitfulness in speech or conduct;
- speaking or acting in two different ways to different people concerning the same matter.
Word Origin
In regular use today, this word originates ultimately from a noun of Latin origin, duplicitās (stem duplicitāt-), formed from the adjective duplex meaning twofold or double. Duplicitous entered English in the early 1890s.
How to use duplicitous
Rather, like his own duplicitous identity, Twain’s texts are double-voiced, both in form and in their equivocal stances toward freedom.
Catching Mark Twain’s Drift | Lawrence Howe, 1998