double-faced vs ingenuous

double-faced

adj
  • deceitful; hypocritical; treacherous 

  • Having two functional faces. 

ingenuous

adj
  • Straightforward, candid, open, and frank. 

  • Unsophisticated; clumsy or obvious. 

  • Naive and trusting. 

  • Demonstrating childlike simplicity. 

  • Unable to mask one's feelings. 

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