If it was a film, it would be a mystery. How did Russell Crowe's The Water Diviner tie with the horror pic The Babadook for the top prize at the country's biggest film and television awards this year?

One was a handsome box office hit backed by such heavyhitters as James Packer and Kerry Stokes. The other was a low budget film from first-time writer-director Jennifer Kent that would have been unknown to virtually everyone who watched the telecast of the Australian Academy of Cinema and Television Arts Awards in January.

Even Cate Blanchett seemed surprised when she announced they had shared the best film award – the first tie for the top prize in the almost 40 years of the Australian Film Institute and AACTA awards – before a live cross to a delighted Crowe on the set of the Hollywood movie he was shooting with Ryan Gosling, The Nice Guys.

Back at the awards at Sydney's The Star, Kent was also delighted. Great television. Winners all round.

While there was widespread puzzlement around the film industry – how do you get a tie in a preferential vote with six nominees? – Academy chief executive Damian Trewhella told the Herald the next day that there was nothing engineered about what he called a dead heat.

"It was a mathematical tie," he said. "It's just a freakish outcome."

But the Herald has now learnt the first count had The Babadook – the little-seen outsider – as a slight winner.

When the "weighted value" of votes for the six nominees were tallied, with six points for a first vote and one point for a sixth, the horror film had 855.5 votes to The Water Diviner's 838.5.

But there was an aberration: The Water Diviner was easily the first choice of most voters but, in either a backlash against the film or its director-star, more voters also placed it last.

That led the academy to running the numbers other ways, including giving a higher weighting to first votes and lower weighting to last votes. That system had The Water Diviner as clear winner.

While not denying the accuracy of these figures, Mr Trewhella said the academy "does not endorse them". But he conceded that rather than a "mathematical tie", there was a decision taken to share the award.

"The result was just too close to call," he said. "The fairest result was to award a tie."

Despite repeated approaches, award scrutineer Ernst & Young would not comment on whether it signed off on the tie.

However, Mr Trewhella said the firm accepted a tie was "a fair result."

It is a rare behind the scenes view that shows the complexities of tallying awards votes.

Complicating the picture was the fact that five of the six nominated films polled very closely.

With 304 of the academy's 1733 members voting, The Babadook led the weighted value votes (18.1 per cent), followed by The Water Diviner (17.8 per cent), sci-fi film Predestination (17.4 per cent), Indigenous drama Charlie's Country (16.9 per cent), wartime survivor drama The Railway Man (16.8 per cent) and outback drama Tracks (13 per cent).

Mr Trewhella described the way the votes fell between The Water Diviner and The Babadaook as "particularly anomalous".

"Ideally it would have been helpful to have a head to head re-vote on these two films to clearly delineate," he said. "However the process does not permit that.

"Hence in the circumstances, as both films were so close to each other in the final standings, the fairest outcome was to award a tie."

Mr Trewhella rejected any suggestion that the higher profile of The Water Diviner influenced the result or that the decision to share the prize affected the integrity of the awards.

"We have had ties before and may well do again," he said. "To not deliver a tie when we feel it is the fairest outcome would be more damaging to the integrity of the awards."

Mr Trewhella pointed out that the Oscars have had six ties in its 87-year history. While there has never been one for best picture, they include Barbra Streisand and Katharine Hepburn sharing best actress in 1969 and Zero Dark Thirty and Skyfall sharing best sound editing two years ago.

And just last year, the Producers Guild of America Awards had a tie for best film between Gravity and 12 Years A Slave.

On whether the voting patterns this year required any change of policy, Mr Trewhella said the academy was "constantly monitoring and evolving processes in order to deliver best award results" but "no substantive change to our award policies [is] planned by the board at this time."

The writer is a member of the academy but did not vote in the awards.

gmaddox@fairfaxmedia.com.au