You need unique form IDs, that is for sure. This part is from @fGo.
<% for(int i=0 ; i<2 ; i++) { %>
<form action="someAction.htm" id="formID_<%=i%>" method="post" class="myform">
</form>
<% } %>
And on document.ready:
$(".myform").ajaxForm({
dataType: 'json',
success: function(response) {
alert("Success");
}
});