Why do events fire twice in webhook telegram bot?

Question

PHP

webhook installed. The script executes the following code:

$content = file_get_contents("php://input");

file_put_contents('log.txt', date('H:m:i d-m-Y') . ' — ' . $content . PHP_EOL, FILE_APPEND | LOCK_EX);
die();

After sending a message to the bot, 2 events come to log.txt, i.e. the script is executed twice.
Because of what it can be?