This does rather look like Amata pactolina, but Walker's original specimen and the 5 BOLD specimens are all from the Northern Territory, see http://v4.boldsystems.org/index.php/Taxbrowser_Taxonpage?taxid=321535 Global warming?
I think the fact that this moth and 4227537 were flying together suggests that the differences in the photos are more likely to illustrate variation within a local species, probably confounded by one of them being well worn, than the presence of a vagrant from N Aust. Amata pactolina has only been recorded in NT and northern WA.