Does Commerce Override Username Or Is Username Linked To A Node?
Commerce Kickstart 2 includes the following function, which uses hook_username_alter() to alter the display of the username to be the billing name, which is what it sounds like you're seeing here.

The easiest way around this would be to just delete this function, which is located in "/profiles/commerce_kickstart/modules/commerce_kickstart/commerce_kickstart_user/commerce_kickstart_user.module" from you're Drupal site's root directory.

/**
 * Implements hook_username_alter().
 */
function commerce_kickstart_user_username_alter(&amp;$name, $account) {
  if (!empty($account-&gt;uid) &amp;&amp; module_exists('commerce_addressbook')) {
    if ($billing_profile_id = commerce_addressbook_get_default_profile_id($account-&gt;uid, 'billing')) {
      $billing_profile = commerce_customer_profile_load($billing_profile_id);
      if (!empty($billing_profile-&gt;commerce_customer_address[LANGUAGE_NONE][0]['name_line'])) {
        $name = $billing_profile-&gt;commerce_customer_address[LANGUAGE_NONE][0]['name_line'];
      }
    }
  }
}