There are several legitimate reasons to own multiple domain names relating to the one website. You might own both the .com and .com.au (or equivalent) to protect others from registering them and causing confusion; popular misspellings to capture visitors who type in your domain name incorrectly, or other domain names that you use to track various offline marketing campaigns.

The best way to handle these is to choose a single, primary domain name. Choose the domain name that the search engines seem to know about (i.e. you search for your business name; the first result that appears is the domain that the search engines primarily associate with your website.) Then, redirect all other domain names to this primary domain. The best type of redirect in this situation is a “permanent redirect”, also known as a “301 redirect”. Your web developer will be able to achieve this for most websites by using what’s known as a “.htaccess file”. Avoid redirects that involve placing code in an HTML page; search engines struggle with these.

“Parking” domain names to your primary website is an easier option, and is usually okay, provided no other website refers to the other domain names. Otherwise, search engines will pick those up, and become confused by the apparent duplicate websites. But to be safe, apply a redirect.