I personally think this should not be a concern. Once you know one language, another one is just similar, just with different grammar/syntax.
Of course there are differences (I know, I deal with C++, Perl, Python, Java, and Tcl on a daily basis, differences in memory management oftentimes drive me crazy), but unless you are specialized in compilers & languages, the differences have little impact on class projects.
My D, when undergrad, seemed to use C++ the most. But now (2nd year PhD), she uses high-level languages (e.g. MathLab) for most of her projects/papers.