How-to display a product variation field twice (or more)? I want simply display a field of a product variation type (commerce) two times with different render settings.

I have tried with a dynamic field (display_suite) but it not working... I would prefer to know a programmatically solution to accomplish this task and I want use the (Drupal core) Display Manager for designate my layout (not a template file) :)

Note: This product field do automatically refresh (ajax) like other when a different product variation is selected.

See this related "issue": https://www.drupal.org/node/1494192#comment-7031370
You should be able to use template_preprocess_node() to duplicate a field.

I've not run this code and just written it from memory but something like this should suffice:

function template_preprocess_node(&amp;$variables) {

  // Check this is the node type for commerce products
  if($variables['node']['#type'] == 'product') {

    // Copy the existing field to a new item
    $variables['content']['YOUR_FIELD_2'] = $variables['content']['YOUR_FIELD'];

    // Now make any changes to how you want to render the duplicate field
  }

}