Abstract: A system and method for controlling duplicate transaction submission in a web browser/web server environment. The client web browser is modified to include a process duplicate action select (e.g. duplicate mouse “clicks”) detection. This process establishes a variable for an action indicating whether the action has been previously selected. Upon selection, the process tests the action variable and passes the transaction request if not previously submitted and returns an error otherwise. The server process has been augmented with a duplicate transaction process. The server software inserts a _tranid parameter into each of a plurality of selected pages returned to a browser for transaction processing. The server maintains a record of the last used jranid. The server compares a tranid returned in a user request to the recorded value. If previously processed, an error is returned to the requester.