Wordpress - 让用户在注册时选择USER ROLE

Question

I have added some functions to my function.php and it works really great. The only problem I see is that when the users Sign Up, its shown twice in "Simple History". That means my function are triggering registration twice?

I am still learning, some help will be highly appreciated.

// URL set USER ROLE

add_action('user_register', 'register_role');

function register_role($user_id, $password="", $meta=array()) {

    $userdata = array();
    $userdata['ID'] = $user_id;
    $userdata['role'] = $_POST['role'];

    //only allow if user role is my_role

    //allow other roles
    if ( ($userdata['role'] == "vip_member") or ($userdata['role'] == "free_member") ) {
        wp_update_user($userdata);
    }
}

add_action('register_form','show_role_field');
function show_role_field(){ ?>
<p>
    <label style="display: block; margin-bottom: 5px;">Role
        <select id="role" name="role" class="input">
            <option value='vip_member'>VIP Member</option>
            <option value='free_member'>Free Member</option>
        </select>
    </label>
</p>
<?php
}