This should not be a problem, however to be able to help, I need to have a better view over your exact setup and logic. Please open a support ticket and send me a sample page that shows the problem and I will check it.
By the way, since you are using RadAjaxManager, you could use ajaxRequestWithTarget for that purpose - then you will not need to change the radconfirm functionality. For your convenience I attached a small sample that shows that approach in action.
the Telerik team