Split Angular js files into their own directories with Ionic

I have just started using Ionic and am trying to modify the gulpfile to watch for js in folders like js/controllers js/services etc so I can split up everything for angular into their own folders and have everything concatenated into one js file to include in index.html

The gulp task I made for this is:

gulp.task('scripts', function() {
  return gulp.src('./www/js/**/*.js')
    .pipe(concat('app.js'))
    .pipe(gulp.dest('dist/js/'))
    .pipe(rename('app.min.js'))
});

gulp.task('watch', function() {
  gulp.watch(paths.sass, ['sass']);
  gulp.watch(paths.js, ['scripts']);
});

This is concatenating all the js into one file but everytime the watcher is trigger it duplicates all the javascript.

How can I get around this?