Submit two forms with one button

A form submission causes the page to navigate away to the action of the form. So, you cannot submit both forms in the traditional way. If you try to do so with JavaScript by calling form.submit() on each form in succession, each request will be aborted except for the last submission. So, you need to submit the first form asynchronously via JavaScript:

var f = document.forms.updateDB;
var postData = [];
for (var i = 0; i < f.elements.length; i++) {
    postData.push(f.elements[i].name + "=" + f.elements[i].value);
}
var xhr = new XMLHttpRequest();
xhr.open("POST", "mypage.php", true);
xhr.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
xhr.send(postData.join("&"));

document.forms.payPal.submit();

You should be able to do this with JavaScript:

<input type="button" value="Click Me!" onclick="submitForms()" />

If your forms have IDs:

submitForms = function(){
    document.getElementById("form1").submit();
    document.getElementById("form2").submit();
}

If your forms don't have IDs but have names:

submitForms = function(){
    document.forms["form1"].submit();
    document.forms["form2"].submit();
}