php help, compare two files on a set time interval and save one of the files if they are not equal.

For my monitoring software. I want to compare the status.json files every five minutes. If there is a difference I want to save the (older) file in the history folder. This took me 2 minutes in bash, but I've been struggling with it the whole day in php.

Function 1, gets called when a status.json file is parsed.

function savefile($bestand,$naam){

    $curdir=getcwd();
    if(!is_dir("{$curdir}/history")){
        mkdir("${curdir}/history") or die("Cannot create history folder. Create it manually and make sure the webserver can write to it.");
    } else {
        $DATETIME=date('U');
        $DATEHOUR=date('H');
        $DATEINT=date('i');

        if (filemtime("${curdir}/${naam}") < (time() - 300)) {
            $local_file=file_get_contents($bestand);
            $saved_local_file=file_put_contents("${curdir}/$naam", $local_file);
        } else {
            $local_file=file_get_contents($naam);
        }

        if ($DATEINT==00 || $DATEINT==05 || $DATEINT==10 || $DATEINT==15 || $DATEINT==59 || $DATEINT==20 || $DATEINT==25 || $DATEINT==30 || $DATEINT==35 || $DATEINT==40 || $DATEINT==45 || $DATEINT==50 || $DATEINT==55) {
            file_put_contents("${naam}.old", $local_file);
            if($DATEINT==00 || $DATEINT==30 || $DATEINT==15 ||$DATEINT==45 ||$DATEINT==59){
                if(!files_identical("${naam}","${naam}.old")) {
                    file_put_contents("history/${naam}.$DATETIME", $local_file);
                }

            }

        }
    }
}

Function 2 (compares the files):

function files_identical($file1, $file2) {
    if (md5_file($file1) == md5_file($file2)) {
        return TRUE;
    } elseif (md5_file($file1) != md5_file($file2)) {
        return FALSE;
    }
}

Somehow this does not work. Also, nothing in the logs (with verbose error logging on). The history folder is created sucessfully, the page is called every 5 seconds from multiple locations (while true; wget $url; sleep 5; done FTW). The other files ($naam.json) and ($naam.json.old) are created sucessfully, only the history folder stays empty. What am I missing here? ( @joepie91 )