Jquery Function Calls More Than One Time?

I am having an aspx page in which I am calling a user control. The user control I am using a pop up to display it when a user clicks a asp:linkbutton. In that user control I am having a textbox and I am calling a Jquery Blur to do some validation. While doing so the function is calling [blur] is calling twice. I just called an alert() with the textbox value.So I can see the alert is coming twice .What I need to do to avoid the second time. I need to do it only whenever the user going out of the textbox and that also one time.

$('#<%=txtCategory.ClientID %>').blur(function() {
alert($(this).val());
});