duple vs two-piece

duple

adj
  • Double. 

  • Having two beats in each foot. 

  • Having two beats, or a multiple of two beats, in each measure. 

two-piece

adj
  • comprising two pieces 

noun
  • A garment consisting of two separate parts; especially such a swimsuit 

How often have the words duple and two-piece occurred in a corpus of books? (source: Google Ngram Viewer )