<?php

    $data = procCSV('data.txt');
    $dataR = procCSV('data2.txt');

    foreach ($dataR as $name => $date) {
    $res = array_search($date, $data);
    if ($res !== false) var_dump($res, $name);
    }

    function procCSV($file) {
        $csv = array_map('str_getcsv', file($file));
        return array_combine(array_column($csv, 0), array_column($csv, 1));
    }