duke out vs get it on

duke out

verb
  • To fight, especially with fists. 

get it on

verb
  • To engage in a fight. 

  • To have sex. 

  • To hurry up; to get a move on. 

  • Used other than figuratively or idiomatically: see get, it, on. 

How often have the words duke out and get it on occurred in a corpus of books? (source: Google Ngram Viewer )