law: Indian Stamp Act, 1899 
  14. Only one instrument to be on same stamp 
  No second instrument chargeable with duty shall be written upon
  
  a piece of stamped paper upon which an instrument chargeable with duty has
  
  already been written:
  PROVIDED  that nothing in this section shall prevent any
  
  endorsement which is duly stamped or is not chargeable with duty being made
  
  upon any instrument for the purpose of transferring any right created or
  
  evidenced thereby, or of acknowledging the receipt of any money or goods the
  
  payment or delivery of which is secured thereby.