double-faced vs treacherous

double-faced

adj
  • deceitful; hypocritical; treacherous 

  • Having two functional faces. 

treacherous

adj
  • Deceitful; inclined to betray. 

  • Unreliable; dangerous. 

  • Exhibiting treachery. 

How often have the words double-faced and treacherous occurred in a corpus of books? (source: Google Ngram Viewer )