Exporting data as two CSV files with PHP, but its stored in one file and also containsHTML tags

Question

I wrote a function in PHP which writes the elements of a two-dimensional array into a CSV file.

function downloadCSV($data)
{
    header('Content-Type: text/csv');
    header('Content-Disposition: attachment; filename="sample.csv"');

    $tmp_array = array();
    $anzSpalten = count($data[0]);
    for ($i = 0; $i < $anzSpalten; $i++) {
        array_push($tmp_array, $data[0][$i]);
    }

    $user_CSV[0] = $tmp_array;
    $index = 0;
    foreach ($data as $row) {
        $tmp_array = array();

        for ($i = 0; $i < $anzSpalten; $i++) {
            if (array_key_exists($i, $row)) {
                array_push($tmp_array, $row[$i]);
            } else {
                array_push($tmp_array, "N/A");
            }
        }

        $user_CSV[$index] = $tmp_array;
        $index++;
    }

    $fp = fopen('php://output', 'wb');
    foreach ($user_CSV as $line) {
        // though CSV stands for "comma separated value"
        // in many countries (including France) separator is ";"
        fputcsv($fp, $line, ';');
    }
    fclose($fp);

}

I want that the files to get downloaded by the browser of the user: Picture of procedure

So far, that works, but there are two problems: I call the function twice with two different datasets, but there's just one file downloaded by the browser containing both datasets. I want them to be stored in two separate files.

if( isset($_GET["send"]) & $_GET["send"] == "Download") 
{
    downloadCSV($wetterDat);
    downloadCSV($sensorDat);
}  

Picture of generated and downloaded csv-file

And as you can see in the file above, somehow, the HTML tags are also added to the CSV file, and that's not my intention.