I need to restrict duplicate events in SharePoint 2010 calendar. Can anyone please provide me step by step approach. I already looked at check booking site column under schedule and reserve content type and that is not I am looking.

I really appreciate your response.


3 Answers 3


I think you can write an event receiver, handle ItemAdding event and cancel any duplicate entry there (you can execute a CAML query for duplicate entries inside an event receiver's logic). You even can write an explaining message to the user.


this depends how many column are involved. There is something that is called force unique values that can be defined per column.

You will find more about that here. http://www.khamis.net/blog/Lists/Posts/Post.aspx?ID=25

The problem is that if more than one column is involved the columns will be check separate instead of all columns together needs to be unique. This is where the best solution is to write a synchronous event receiver.


Following options to achieve it

  1. We can enable the Enforce Unique Value option to the Field
  2. By using ItemAdding event handler, we can check the new item with old items and prevent the user from adding items.

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