Keep in mind that Australian Customs is a federal body, and firearm laws (including replica firearms) fall under individual state/territory jurisdictions. Hence why, for example, owning Gunformers is completely unrestricted in WA, legal w/ a permit in NSW, and completely outlawed in other places. As a permit-holding NSW resident, if I attempted to import a Gunformer it can still be intercepted and seized by Australian Customs because my permit was issued in NSW. Customs would then notify me of the seizure, and it would be then up to me to present my permit to Customs for the toy to be released to me.

I don't know so much about Victorian laws, but that's how it would work in NSW AFAIK.