proper way to do different submits

propersubmit.php

<?php

namespace Drupal\general\Form;

use Drupal\Core\Form\FormBase;
use Drupal\Core\Form\FormStateInterface;

/**
 * List tests arranged in groups that can be selected and run.
 */
class TestForm extends FormBase {

  /**
   * {@inheritdoc}
   */
  public function getFormId() {
    return 'testform';
  }

  /**
   * {@inheritdoc}
   */
  public function buildForm(array $form, FormStateInterface $form_state) {

    $form = [
      'sub' => [
        '#type' => 'container',
        'submit' => [
          '#type' => 'submit',
          '#value' => 'Sub me too!',
          '#name' => '2',
          '#submit' => ['::dumptwo'],
          '#weight' => 2,
          '#parents' => [2],
        ],
      ],
      'submit' => [
        '#type' => 'submit',
        '#value' => 'Sub me!',
        '#name' => '1',
        '#submit' => ['::dumpone'],
        '#weight' => 1,
        '#parents' => [1],
      ],
    ];
    return $form;
  }

  /**
   * {@inheritdoc}
   */
  public function dumpone(array &$form, FormStateInterface $form_state) {
    dump(1);
  }

  /**
   * {@inheritdoc}
   */
  public function dumptwo(array &$form, FormStateInterface $form_state) {
    dump(2);
  }

  /**
   * {@inheritdoc}
   */
  public function submitForm(array &$form, FormStateInterface $form_state) {
    // meh.
  }

}