bicolour vs duocolor

bicolour

adj

  • Having two colours 

noun

  • A flower, cat etc., that has two colours. 

  • A flag with such colours, consisting of two stripes that are either vertical or horizontal. 

duocolor

adj

  • Having two colors. 

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