New Record Insert While page Refresh each time

Question

If new record is added and then page is refresh then add duplicate record automaticallly.I solved this problem in many ways from code behind. 
I solved this also by adding update panel on the page .but i dont understand why this problem occure because i think this is not proper way. 
I think there is no need to add extra code to handle such problem . 
so pls tell me if any suggessions