Are there any issues with multiple user writing to sharepoint list simultaneously, concurrency issue

ChrisWebbTech Thanks for the reply.
i have actually created such a mechanism already using another list to track the users when they are in edit mode.
But tracking how the exit the page is a tough one (currently if they click the back button or click a specific link to go back its all good and it works) as they can just closed the browser (So i like the idea where you suggested to have a timer and if exist after certain time it automatically removes the user)

Thanks for the idea 🙂