Especially if one of them is based off the other.
Rust is based off of C/C++
Ruby is based off of Perl, Smalltalk, Eiffel, Ada, BASIC, Java, and Lisp
Just a couple of examples. Quite frankly, it's dependent on what system, what infrastructure .etc that'll be the call for a specific programming language. Nothing wrong with just picking one or two and sticking to them.
And I think that's what a lot of beginners in wanting to study programming languages can fall into, they want to be the jack of all trades in programming. But there's this problem of a new language coming in all of the time and it can get very wiry trying to remember them all.