This piece of code in function contact_mail_page()

      $form['name'] = array('#type' => 'textfield',
        '#title' => t('Your name'),
        '#maxlength' => 255,
        '#default_value' => $edit['name'],
        '#required' => TRUE,
      );

was modified with:

      $form['contactname'] = array('#type' => 'textfield',
        '#title' => t('Your name'),
        '#maxlength' => 255,
        '#default_value' => $edit['name'],
        '#required' => TRUE,
      );

Reasons:

A form element with ID="name" already exists in the user login form. If both forms are displayed in the same page this make not valid the XHTML code.