I can surely say that this is bug of jquery 1.9.1. Below is the hack cum solution i have done.
In button declaration I have put condition-when dialog box is open then only button callback function execute. Look at the below button declration.
buttons: [{
text: "Ok",
id : "btnModalDialog",
Click : function () {
var isOpen = $("#dialog-confirm").dialog("isOpen");
if (isOpen == true) {
okCallBack();
}
$("#dialog-confirm").dialog("close");
}
}]