A duplicate AJAX request occurs when a user clicks on a link that sends a request to perform an operation, and, before receiving the response, clicks again on the same link. This causes two AJAX requests with the same operation ID to be submitted for processing to the server side at the same time. The server receives and processes both requests, leading to the user send the same request two or more times.

When duplicate AJAX requests are made, only the first and the last AJAX requests are processed, and all other duplicate requests are ignored on the server side.

It is recommended that application developers identify the areas in which duplicate AJAX requests might be made during the application development stage. This prevents the need for the server side to handle duplicate requests.