title: pressing two keys are giving me a bug
body: <p>I have been trying to fix this bug where when you press two buttons at the same time and realse one of them the character in pygame doesn't move to the button that's pressed down.</p>
  <pre><code>def tank_control(event):
      if event.type == KEYDOWN:
          if event.key == K_UP:
              tanks_list[0].accelerate()
          elif event.key == K_DOWN:
              tanks_list[0].decelerate()
          elif event.key == K_LEFT:
              tanks_list[0].turn_left()
          elif event.key == K_RIGHT:
              tanks_list[0].turn_right()
      elif event.type == KEYUP: 
          if event.key == K_DOWN or event.key == K_UP:
              tanks_list[0].stop_moving()
          if event.key == K_LEFT or event.key == K_RIGHT:
              tanks_list[0].stop_turning()
  </code></pre>