Two-faced

What does two-faced mean?

Someone who is two-faced is someone who is not sincere, someone who is deceptive.

Two eyes on one side? That is Isis.
For beauty she sure took no prizes.
But Janus had faces
In two different places,
Which was an identity crisis.

I wish to express my admiration for that limerick. Imaginative and funny, not to mention informative. SS

I had lots of time on my hands in college. More:
In heaven there'll be enough room
to fit in Locke, Berkeley, and Hume.
They'll have to finagle
To squeeze in Herr Hegel,
And Freud must return to the womb.