Also, friend of mine is doing their masters at monash and finishing his diploma of languages at melbourne right now.
Cool, what language is he/she studying?
Is it arabic?
Why doesn't he/she do his diploma at monash? 
So, generally speaking in Australia, can you only do two degree at two different universities if you're doing one of them via distance ed or through open universities?
No, lawl not arabic, Japanese. Not sure why, just finishing a diploma he began in his undergrad from Melbourne.
And also no, you can do two degrees simultaneously if you get approved to do them, like i know its possible to do some part-time uni courses on top of another, just need approval for the second if its not via open uni.
like you can start your masters at some unis while already doing an undergrad if you get in, etc