Could have sworn there were fewer seats available on the second night of the Sydney show, what with the top tier closed off and all... but if it's on Wikipedia then I shall not question it.
I'd say they've used the figures from the second night as the numbers for both, to make it look like they sold out both nights. Those numbers dramatically reduce the capacity of both Acer and Rod Laver. The first night in Sydney had at least 17,000. At least.
I believe the first night was 14,500 (capacity) and the second night looked to be somewhere around the 9,000 mark. But yes, interesting figures... Hmmm...