Itemupdating event fires twice
Writing that makes your world pink and sparkly again.But this is the barren end empty world of the remote event receiver and no such this is available.One reason to prevent events from being raised is to avoid recursion.For example, if you have an Item Added event on a list and you write code within it to add an item, you can put that code in a Disable Event Receivers() ... When you add a new item, only the Item Adding() event is raised.
To see a workaround for this see the following KB: There are likely other causes for event receivers running more than once but these are the two that I run into the most while working with customers.
Assume an exception occurs, the code will never reach the line where the event firing is enabled (restored) again.
Why does my event receiver / handler run more than once when I update or add a new list item?
It also checks for a null title or a title that does not equal "Title Updated in Item Updated".
If it finds either it updates the Title field of the current item.