bis vs twofold

bis

adv
  • Twice; showing that something is, or is to be, repeated, such as a passage of music, or an item in accounts. 

twofold

adv
  • In a double degree; doubly. 

adj
  • Double; duplicate; multiplied by two. 

  • Having two parts, especially two different parts. 

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