Website Duplication or another way

I work for a company that started in Australia and is now expanding into the US. We have a .com.au domain and the .com of our website is not available unfortunately. We are hosted in Hubspot and making considerations for launching a duplicate website (.us) to get better traction in US searches. We have pretty solid SEO on our .com.au site today but concerns we are not showing up for those IP addresses searching from the US. How would you recommend we start looking to solve for this? I have read several articles that frown upon site duplication for several reasons.