Optus are currently offering a 50% discount on your second service when you port it in. I just signed up in store and was told if you upgrade or sign up a new mobile plan you can get a 50% discount on any additional mobile services if you port in from another provider.
For $73.50 per month I got both my partner and I on their $49 plan with 120GB of data to share between us. I asked the sales rep in store this can be done on any of their “choice” sim only and handsets plans.
However, I cannot find the deal on their website so you may need to ask for it in store