Description:
------------
Pdo-mysql prepared statements execution fails when one named parameter appears 
more than once in a SQL statement. 

This problem will disappear if set PDO::ATTR_EMULATE_PREPARES to true.

Test script:
---------------
//CREATE TABLE `posts` (
//  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
//  `name` VARCHAR(255),
//  `body` TEXT
//);

$pdo->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);

// :search appears twice here
$stmt = $pdo->prepare('SELECT id FROM posts WHERE name LIKE :search OR body LIKE :search'); 
$s = 'blablah';
$stmt->bindParam(':search', $s);
$stmt->execute(); // This step throws an exception: Error: SQLSTATE[HY093]: Invalid parameter number
// $stmt->execute([':search'=>$s]); will throw it too
$result = $stmt->fetch();

Expected result:
----------------
No exceptions.

Actual result:
--------------
$stmt>execute fails.

Error: SQLSTATE[HY093]: Invalid parameter number