I have been doing French and German at TAFE for the past year and when I start Uni next year will do French and German.
I contacted ANU and they advised it is definitely possible to do 2 languages at once.
The only problem with learning 2 at once usually comes if you learn 2 languages from the same group, as you might easily mix them up, French and Spanish are from the same group, so that might be your only problem. But if you can get around that you should be fine, also if you learn 2 languages from the same group – but one first on its own, then the second one will be easier for you.
I have found doing both French and German at the same time not a problem at all. But they are both from different language groups so it makes it a bit easier, and the German is very very easy (similar to English in so many ways).
Good Luck.