This note is two different notes, one with overprint and one without (the picture is the one with the overprint):
Could it be split? I think it makes sense to have the overprint seperated, since it's a differance, visible with the naked eye.
Sources:
http://www.banknote.ws/COLLECTION/countries/AUS/NCD/NCD0059.htm
http://www.banknote.ws/COLLECTION/countries/AUS/NCD/NCD0063.htm