PHP script that removes duplicate fields in a csv

script.php

<?php

if ($argc < 2) {
    exit('Error: No CSV file provided. Example usage: php script.php input.csv' . PHP_EOL);
}

if (pathinfo($argv[1], PATHINFO_EXTENSION) !== 'csv') {
    exit('Error: Provided file is not a CSV.' . PHP_EOL);
}

$inputCsv = $argv[1];

function parseCsv(string $csvFile): array {
    return array_map('str_getcsv', file($csvFile));
}

function findUniqueRows(array $data): array {
    $serializedRows = array_map('serialize', $data);
    $uniqueSerializedRows = array_unique($serializedRows);
    return array_map('unserialize', $uniqueSerializedRows);
}

function updateCsv(string $csvFile, array $uniqueData): void {
    $fileHandle = fopen($csvFile, 'w');

    foreach ($uniqueData as $fields) {
        fputcsv($fileHandle, $fields);
    }

    fclose($fileHandle);
    echo "CSV file updated with unique rows." . PHP_EOL;
}

function writeDuplicatesCsv(string $inputCsv, array $originalData, array $uniqueData): void {
    $duplicateData = array_udiff($originalData, $uniqueData, 'strcmp');
    $duplicateCsvFile = pathinfo($inputCsv, PATHINFO_DIRNAME) . '/duplicates_' . pathinfo($inputCsv, PATHINFO_FILENAME) . '.csv';
    $fileHandle = fopen($duplicateCsvFile, 'w');

    foreach ($duplicateData as $fields) {
        fputcsv($fileHandle, $fields);
    }

    fclose($fileHandle);
    echo "Duplicates written to: $duplicateCsvFile" . PHP_EOL;
}

$data = parseCsv($inputCsv);
$uniqueData = findUniqueRows($data);
updateCsv($inputCsv, $uniqueData);
writeDuplicatesCsv($inputCsv, $data, $uniqueData);

Regarding comment on Line 23, can the unique function create a new csv file to write the duplicate values/rows?
Purpose: To compare the duplicates removed from the unique values for analysis.
Thank you.