Duplicate Content .com & .com.au of same domain

Hello Friends,
I have one website around 8 years old in domain.com, now our partner activated new domain ie; domain.com.au with the same content.
My query: it will affect to SEO and keyword ranking, etc…
In .com website many keywords are indexed in Google index 1st page.
Please advise me how to take it forward.

See original post by ponmayil