How can I access multiple individual reCAPTCHA responses from the same page?

Question

I have multiple reCAPTCHAS on the same page, and all reCAPTCHAS return $_POST['g-recaptcha-response'] by default. Is there a way so that I can change the $_POST name for each Recaptcha, and therefore access the individual responses of them?

If my site keys / secret keys are the same, will this mean that I can't access the individual responses?

Thanks for the help! :)

HTML:

<div class="g-recaptcha" id="recaptcha1"></div>
<div class="g-recaptcha" id="recaptcha2"></div>

jQuery:

var recaptcha1 = $("#recaptcha1");
var recaptcha2 = $("#recaptcha2");
var myCallBack = function() {
    //Render the recaptcha1 on the element with ID "recaptcha1"
    recaptcha1 = grecaptcha.render('recaptcha1', {
    'sitekey' : 'removed_for_demonstration',
      'theme' : 'light'
    });

    //Render the recaptcha2 on the element with ID "recaptcha2"
    recaptcha2 = grecaptcha.render('recaptcha2', {
      'sitekey' : 'removed_for_demonstration',
      'theme' : 'light'
    });
};

PHP:

$captcha = isset($_POST['g-recaptcha-response']) ? $_POST['g-recaptcha-response'] : "";