I have been teaching programming for several years, so I can share my experience with you. I assume that C# is your first language, so my experience teaching programming to people that had never programmed before may be useful.
First of all, let me tell you that learning more than one language is something that every seasoned programmer should do. But this does not mean that you should learn several languages at the same time if you are just starting.
Over the years, students have shown that it takes about a year for a language to solidify in the mind (at least the first one), sometimes a little more, sometimes a little less. If you try to teach more than one language in one year students tend to mix them up and confuse concepts and languages. Although students make progress, they get into a lot of bad habits that is difficult to weed out later. If you are learning on your own, this risk is higher.
However, I have noticed that it helps if you teach two languages with a very different syntax. When two programming languages look really different it helps the mind to see them as really different entities without polluting each other. (When one programming language helps you understand difficult concepts in another language, that is good; when one language makes you write bad code in another language, that is bad).