I'm currently taking Italian lessons (my third year), and from what I've heard of other people, it's better not to learn Spanish and Italian at the same time, because they are similar but different. You  make more mistakes, because it's sometimes confusing, like when you're using the word "agua" instead of "aqua" when you talk Italian.

I don't think learning 2 different languages with different roots (like Spanish and German) is a bad idea. When I was in high school, we were taught French, German, English and Latin at the same time (in addition to Dutch, our native language).