Early in the voting period, it was revealed some voters had received duplicate voting packs. An investigation found a file containing up to 500 elector records was printed twice.
Shortly after, it was also revealed two people had received 39 voting packs.
The electoral office's software does not allow more than one vote per person.
The information was contained in a report by Election Services which is being presented to the Whangarei District Council meeting tomorrow.
The printing company took full responsibility for the error, and has paid $5000 plus GST to the council as compensation.
That payment was deducted from the cost of the by-election, which reduces it from $31,127.51 plus GST to $26,127.51 plus GST.
The report states Election Services "no longer have arrangements with this printer".
Gavin Benney won the by-election with 841 votes, ahead of Matt Keene with 635 votes.
There were 14,135 eligible voters and 32.04 per cent, or 4529 people, returned their vote.