You make it sound like it was difficult to learn. Underneath, C++, Java, Pascal, C#, Javascript and Python, have many similarities and jumping from one of those languages to another in the list is very easy; compared, for example, to something like jumping from any of those languages to Forth, PROLOG, SQL, ML, Haskell, or Lisp.
Some of them are also really similar syntactically, for example this group: [C, C++, Java, C#]; or this other group: [Pascal, Algol, Go], so even the syntax doesn't get in the way when jumping from one to other.
Thus, usually, software engineers do know more than one language and they apply what better suits the program.
You make it sound like it was difficult to learn. Underneath, C++, Java, Pascal, C#, Javascript and Python, have many similarities and jumping from one of those languages to another in the list is very easy; compared, for example, to something like jumping from any of those languages to Forth, PROLOG, SQL, ML, Haskell, or Lisp.
Some of them are also really similar syntactically, for example this group: [C, C++, Java, C#]; or this other group: [Pascal, Algol, Go], so even the syntax doesn't get in the way when jumping from one to other.
Thus, usually, software engineers do know more than one language and they apply what better suits the program.