An interesting claim in the government fact sheet that is new to me. Personally I had never seen any other evidence that Bactrian camels were brought to Australia (minutes of acclimatisation societies, photos of camels etc) and all other references I have read only mention dromedaries. However I did find another source that makes the following claim:
An estimated 10,000 to 12,000 camels, imported into Australia between 1860 and 1907, were used as draft and riding animals by people pioneering the dry interior.
The camels brought into Australia were almost exclusively the one-humped camels (Camelus dromedarius) which are found in hot desert areas and are highly suited to the climate in Australia. Only about 20 of the two-humped camels (Camelus bactrianus) normally found in cold deserts were imported into Australia. Camels Australia Export - Central Australia - Northern Territory - Australia
A bit of background reading indicates that the two species can interbreed, and that the resulting progeny is a single humped camel.
So it seems some bactrians did come to Australia, but they probably either interbred with the vastly larger numbers of dromedaries or just died out, leaving the Australian population to a larger or lesser degree a hybrid population of one humped camels.
However there is no population of feral or captive two-humped Bactrian camels existing in Australia today.