like two peas in a pod vs selfsame

like two peas in a pod

prep
  • Very similar; a couple made for each other. 

selfsame

adj
  • Chiefly preceded by the: precisely the same; the very same; the same not only in being similar but in being identical. 

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