get on to vs get to know

get on to

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

  • To contact (someone) in order to raise or discuss a certain matter. 

  • To progress to; to start working on. 

get to know

verb
  • Used other than figuratively or idiomatically: see get, know. 

  • To become acquainted with (someone or something); to meet someone. 

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