Stop second lightbox from appearing
I have a lighbox that opens when one of the download buttons is clicked but I've noticed a second empty lightbox opens in the top left corner too, I'm guessing it's to do with the 'show' command on both the form and the onSuccess but what do I need to change to prevent this second one from appearing?

<script src="//go.wilmingtonplc.com/js/forms2/js/forms2.min.js"></script>
<form id="mktoForm_13497"></form>
<script>var instanceURL = "//go.domain.com", munchkinId = "000-XXX-000", formId = 13497;
var gateLinks = document.querySelectorAll(".lightboxGated"),
ready = function(form){
form.addHiddenFields({
"axcoLastReportID" : this.id
});
MktoForms2.lightbox(form).show();
};
[].forEach.call(gateLinks,function(link){
link.addEventListener("click",function(e){
MktoForms2.loadForm( instanceURL, munchkinId, formId, ready.bind(this));
e.preventDefault();
});
});
</script>
<script>MktoForms2.whenReady(function (mktoForm) {
MktoForms2.lightbox(mktoForm, { onSuccess: showThanksEl }).show();
function showThanksEl(vals, thankYouURL) {
var formEl = mktoForm.getFormElem()[0],
thanksEl = document.createElement("DIV");
thanksEl.innerHTML = "<div class='popUp'><h2 style='color: #ff4338; text-align: center;padding-top:10px;'>Thank you! </h2><p style='color: #0C2340; font-size: 16px; text-align: center;padding:20px;'>Your selected report has been sent to the email address provided</p></div>";
formEl.parentNode.replaceChild(thanksEl, formEl);
return false;
}
});</script>