Does adding a CSS class programatically add multiple instances of that class if the reference already exists?

Does adding a CSS class programatically add multiple instances of that class if the reference already exists?

Does adding a CSS class programatically via  add multiple if it already exists? IOW, with code like this:

  1.   'change #date1Shift1JobLoc1Count': function(event) {
        var d1s1jl1Count = $('date1Shift1JobLoc1Count').val();
        if (d1s1jl1Count > 1) {
          $('date1Shift1Worker5').removeClass('hide');
        } else {
          $('date1Shift1Worker5').addClass('hide');
        }
      }

..if date1Shift1Worker5 already had the class 'hide' applied to it, would an additional 'hide' be added and, if so, is that a problem other than maxifying the CSS?