For example, if you define an instance level variable in the class to store data in the As per the first look of Developers, we say simply, Item Updating and Item Updated events are fire twice when we adding a document to a document library that has the Require Check Out option enabled.This is not either issue with Share Point or issue with Custom Code.Turning off the Require Check Out option is a great quick fix if you don’t require the item to be checked out in order for it to be edited.But that option exists to be used, and some people really do need it.
If you were to check the document out and edit the properties on the document, you would see the Item Updating and Item Updated events fire once.
So the net result of this is that the document is uploaded and the Item Adding and Item Added events have fired, which is pretty much what you would expect.
Next, let’s look at what happens when the user adds a document when the Require Check Out option is enabled.
If you wish to modify a property value on the list item during the event, the value should be updated in After Properties property of the properties parameter.
Share Point reads these values from the event parameter and modifies the item accordingly when the actual operation runs (e.g.