second string vs superfluous

second string

adj
  • Not as good; of a lower quality or condition. 

noun
  • A unit of players which is considered to have a secondary level of talent and which usually plays after the first string. 

superfluous

adj
  • In excess of what is required or sufficient. 

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