Is a Double Degree equivalent to 2 single degrees?
I took a double degree in Electronic Engineering and IT (Computer Science) from QUT. It required more time than either of the single degrees, and the course load was considerably higher per semester. At graduation, I received two separate degree certificates from QUT — I have two Bachelor degrees. There were some restrictions in the number of elective subjects we could take, since the core course load was higher.

Of course you need to check the course content and course load (and duration — a Bachelors degree without honours in Australia is usually three years, not four), to be certain it's right for you.