Are you thinking of a phishing attack? A phishing attack involves tricking a user into entering credentials into a website that looks much like a legitimate one.
For example, suppose First World Bank has the domain name of firstworldbank.com. Eve, the attacker, might create firstw0rldbank.com or flrstworldbank.com. She then sends an email to Bob that claims his passsword needs to be renewed, with a link to one of the fake websites. If Bob falls for the trick and logs in, he loses his credentials.
I seriously doubt this is a phishing attempt, however!
A cursory glance at both websites shows that they have significantly different layouts and content. It's much more likely that two different people decided that "top bargain" is a good name for a coupon-related service.
They are the same website, or, at least, appear to be so. The .org domain contains a traffic-monitoring script, but otherwise appears to be the same. They also resolve to different IP addresses. I'm not a web guru, so I can't say if this is suspicious or not.
As a precaution, though, you may want to query the customer support of the .com.au domain. I'm certain they'll let you know if the other site is legitimate or not.