The Australian Electoral Commission through its acting electoral commissioner Tom Rogers admitted to more election blunders in an interview with ABC's AM program.

Mr Rogers was still answering questions and criticism about the controversial lost of 1,370 ballot papers during the September election 2013. The controversy caused his superior Ed Killesteyn to resign.

On Tuesday, Justice Hayne, sitting as the Court of Disputed Returns, ruled for a re-election in Western Australia, upholding that the loss of the ballots altered the closing results.

The controversy did not stop there as Mr Rogers admitted that the re-election might cost taxpayers an excess of $20 million.

"Twenty million dollars, and that does not include public funding which I think is, will be in the order of $3 million I think," Mr Rogers told ABC's AM program.

AEC also admitted that the by-election caused by former Prime Minister Kevin Rudd cost taxpayers more than $1 million.

Mr Rogers apologised for the commission's electoral blunders.

However, a more alarming issue was exposed as Mr Rogers revealed that almost 2,000 people casted their votes for the Sept 2013 election more than once, as many as 15 times - with one person assumed of filling-out 15 ballots.

"One thousand, nine-hundred and seventy-nine electors have admitted to voting more than once, with the greater majority of those, over 81 per cent, being elderly, with poor literacy, or with a low comprehension of the electoral process," Mr Rogers said.

Liberal Senator Dean Smith asked for Mr Rogers to give the specific ratio of person per ballot.

Mr Rogers said that 22 voters had voted four times; five voters voted for four times; six voters voted for seven times; one voter voted for nine times; one voter voted for 12 times and another one voter voted for 15 times.

Mr Rogers said that the commission had already asked the federal police to investigate multiple voting. He also explained that those voters as observed were elderly, less educated and clueless of the whole electoral process.