How I can fix "Cannot redeclare" error in PHP? - php

Question

When the language string is "en" I get this error:
Fatal error: Cannot redeclare getSetting() (previously declared in /Users/manuel/Sites/WebApply/datamanager.php:2) in /Users/manuel/Sites/WebApply/datamanager.php on line 10
I have already tried to change the require imports to require_once but without success.
index.php
if(!file_exists("mysql.php")){
header("Location: setup/index.php");
exit;
}
require_once("datamanager.php");
require_once('assets/languages/lang_'.getSetting("lang").'.php');
datamanager.php
<?php
function getSetting($setting){
require_once("mysql.php");
$stmt = $mysql->prepare("SELECT * FROM settings WHERE NAME = :setting");
$stmt->bindParam(":setting", $setting, PDO::PARAM_STR);
$stmt->execute();
while ($row = $stmt->fetch()) {
return $row["VALUE"];
}
}
function setSetting($setting, $value){
require_once("mysql.php");
$stmt = $mysql->prepare("UPDATE settings SET VALUE = :value WHERE NAME = :setting");
$stmt->bindParam(":setting", $setting, PDO::PARAM_STR);
$stmt->bindParam(":value", $value, PDO::PARAM_STR);
$stmt->execute();
}
function getRankID($username){
require_once("mysql.php");
$stmt = $mysql->prepare("SELECT * FROM accounts WHERE USERNAME = :user");
$stmt->bindParam(":user", $username, PDO::PARAM_STR);
$stmt->execute();
while ($row = $stmt->fetch()) {
return $row["USERRANK"];
}
}
?>