I’ve lived in NZ for 20 years now. To the untrained ear, the differences between an Aussie and a Kiwi accent are generally tok subtle.
While Michelle is indeed from NZ, she is not speaking in her normal voice as Omega. Although Wikipedia says she was invited to keep her NZ accent, it sounds to me more like she has been putting on an Aussie twang to sound more like Dee Bradley Baker, who also ended up making the clones sound more Australian than Kiwi.
Here’s an example of Michelle’s normal voice:
If you know what to listen for, you can hear the difference between her normal voice and her Omega voice.
@Zardnaar can back me up. He’s even from the South Island like Michelle!