Police will be called in to investigate 128 cases where Australians voted more than once in the 2013 federal election, with one person suspected of voting 15 times.

At the high end, the Australian Electoral Commission claims there are numerous electors who voted up to seven times, with one person alleged to have voted nine times, another 12 times and one 15 times.

''We sent inquiry letters to 18,770 electors who had multiple marks recorded beside their names,'' AEC acting head Tom Rogers told a Senate estimates hearing on Tuesday.

Replies are still being processed but more than 8200 have been ruled out as ''official error''.

Another 1979 people have admitted voting more than once.