http://michaelbrockman.wordpress.com/2010/11/10/deployment-conflict-resolution-in-visual-studio/
If you are provisioning a ListInstance in Visual Studio you may see the following error message:The URL or name of this list instance conflicts with a list instance already on the server.
The list instance on the server will be deleted before deploying the new list instance.
If you select Resolve Automatically, your list and all of its data will be removed before a new instance of the list is provisioned. To prevent this, you can set the Deployment Conflict Resolution property of the list instance in the Solution Explorer to None. Simply right-click on the list instance project item in VS and select Properties. Then select None from the dropdown list of values:
