Gulp Concat + Uglify order JS error

Question

I'm trying to concat and uglify javascript files in a specific order. When i disable uglify it works well as i order. But when i turn on uglify, the JS order is ignored. What am i doing wrong?

Script_1.js

let script_one = () => {
   console.log(1);
};

Script_2.js

let script_two = () => {
   console.log(2);
};

Gulp Task

gulp.task('js', function() {
    return gulp.src(['js/Script1.js', 'js/Script2.js'])
      .pipe(rigger())
      .pipe(concat('main.js'))
      .pipe(babel({presets: ['env']}))
      .pipe(uglify())
      .pipe(gulp.dest('dist/js'));
});

Output

var script_two=function(){console.log(2)};var script_one=function(){console.log(1)};

Expected Output

var script_one=function(){console.log(1)};var script_two=function(){console.log(2)};

Output without Uglify

  var script_one = function(){
     console.log(1)
  };
  var script_two = function(){
     console.log(2)
  };

Thanks!!