Digital signatures from the form and in the handler are not equal?

Question

PHP

https://help.unitpay.ru/article/31-creating-paymen... It says that the digital signature that is sent to the handler:

function getFormSignature($account, $currency, $desc, $sum, $secretKey) {
    $hashStr = $account.'{up}'.$currency.'{up}'.$desc.'{up}'.$sum.'{up}'.$secretKey;
    return hash('sha256', $hashStr);
}

https://help.unitpay.ru/article/35-confirmation-payment It is already said here that a digital signature:

function getSignature($method, array $params, $secretKey) {
    ksort($params);
    unset($params['sign']);
    unset($params['signature']);
    array_push($params, $secretKey);
    array_unshift($params, $method);
    return hash('sha256', join('{up}', $params));
}

In other payments, I would just compare digital signatures. But here, in the signature generation in the handler, $method is added, which is not in the digital signature from the form on the site. They won't be exactly the same. What to do? Tell me please..