carbon copy vs like two peas in a pod

carbon copy

noun

  • A duplicate copy of an email. 

  • A copy produced in an alternated stack of ordinary sheets of paper and carbon papers. The pressure applied on the top sheet (by a pen or typewriter) causes every carbon paper to release its carbon cover, thus reproducing the writing on the subjacent layers of paper. 

  • Any duplicate. 

verb

  • To send a duplicate copy of an email to. 

  • To create a carbon copy of. 

like two peas in a pod

prep

  • Very similar; a couple made for each other. 

How often have the words carbon copy and like two peas in a pod occurred in a corpus of books? (source: Google Ngram Viewer )