diff --git a/email_registration.module b/email_registration.module
index e12b5c972e3c10c470c83c296213cbaac9a2d5b3..dc77ef450ef5dc274a8f9313f8f1913168c456f9 100644
--- a/email_registration.module
+++ b/email_registration.module
@@ -9,6 +9,11 @@
  * Implements hook_user_insert().
  */
 function email_registration_user_insert(&$edit, &$account, $category = NULL) {
+  // Don't create a new username if one is already set.
+  if (!empty($account->name) && strpos($account->name, 'email_registration_') !== 0) {
+    return;
+  }
+
   // Other modules may implement hook_email_registration_name($edit, $account)
   // to generate a username (return a string to be used as the username, NULL
   // to have email_registration generate it).
@@ -59,7 +64,7 @@ function email_registration_user_insert(&$edit, &$account, $category = NULL) {
  */
 function email_registration_form_user_register_form_alter(&$form, &$form_state, $form_id) {
   $form['account']['name']['#type'] = 'hidden';
-  $form['account']['name']['#value'] = user_password();
+  $form['account']['name']['#value'] = 'email_registration_' . user_password();
   $form['account']['mail']['#title'] = t('E-mail');
 }