This is really neat! I am doing a lesson a day on DuoLingo for: Danish, Dutch, French, German, Irish, Italian and Portuguese.
I don't have any deadline for learning, so I'm okay with taking it slowly and building the language-learning habit. If I have extra time at the end of a day, I do review mode or practice translating materials in Spanish or French.
Don't worry, I have a mind for languages, so I do not confuse similar ones. : )