genuine note
number of the Block corresponds to the last number of the serial # (in the above case 3)

contemporary counterfeit, punched "Falso"
last number of the Block does not correspond to the last number of the serial # (in the above case 6 and 9)
further this counterfeit can be recognized by a spelling error in the 6th line of the small text on front:
"angenemmen" instead of correct spelling "angenommen"

Note: the are, however, counterfeits with correct spelling of "angenommen". Those may be recognized by mismatching final numerals of Block and serial #