doubling vs repetition

doubling

noun
  • The act of turning around, or doubling back. 

  • A pleat or fold. 

  • The process or an instance of making something double; a multiplication by two. 

repetition

noun
  • The act or an instance of repeating or being repeated. 

  • The act of performing a single, controlled exercise motion. A group of repetitions is a set. 

verb
  • To petition again. 

How often have the words doubling and repetition occurred in a corpus of books? (source: Google Ngram Viewer )