Error: A duplicate field name "xxxx" was found

Soon I have some experience with migrating solution from SharePoint 2010 to SharePoint 2013.

The migration was on 3 steps. First one was just to copy the custom fields, content types and list definitions from the old VS 2010 project into a new VS 2012 project for SharePoint 2013. Looks like pretty simple task but …..

The problem:  Error “A duplicate field name "xxxx" was found” when the feature for provisioning the fields and content types is activated.

The solution: Review the field definitions and make sure no field has Name property equal to some of the ‘reserved’ values.

Explanations:

In SharePoint 2010 there was no problem to have these fields as a definition of custom fields:

<Field    Type="Note"
    ID="{893FB9BC-2DA4-4451-A1D1-88010CDC6A08}"
    Name="Description"
    StaticName="Description"
    DisplayName="Description 1"
    Required="FALSE"
    MaxLength="1024"
    Group="Group 1" />
  <Field    Type="Note"
    ID="{854FBE55-1282-43A6-9D98-3EE5EB21597D}"
    Name="Description"
    StaticName="Description"
    DisplayName="Description 2"
    Required="FALSE"
    MaxLength="1024"
    Group="Group 2" />

Here, the Name and Static Name are equal while the ID property is different.

If you move this in the SharePoint 2013 solution the error “A duplicate field name "Description" was found.” will appear on feature activation.
Even if you remove the second field and deploy only the first one - the error will appear !

The interesting part here is that we still can have fields with one and the same Name property but they should not be from the ‘reserved’ once. I have determinate three of these ‘reserved’ fields while migrate - Description, StartDate, EndDate. 

If we change the above definition to the following one, the deployment will succeed:

<Field    Type="Note"
    ID="{893FB9BC-2DA4-4451-A1D1-88010CDC6A08}"
    Name="MyDescription"
    StaticName="Description"
    DisplayName="Description 1"
    Required="FALSE"
    MaxLength="1024"
    Group="Group 1" />
  <Field    Type="Note"
    ID="{854FBE55-1282-43A6-9D98-3EE5EB21597D}"
    Name="MyDescription"
    StaticName="Description"
    DisplayName="Description 2"
    Required="FALSE"
    MaxLength="1024"
    Group="Group 2" />

Even if this will succeed I will suggest you two things:

     first – keep Name and Static name equals

     second – don’t use fields with equal Name property. We can move ahead with only one field. Also using the web interface for editing them we will experience the following behavior: editing the second column listed in the Site Columns page will edit the firs column. What I mean?

If we deploy our fields we will see the following:

If we click on the field “Description 2” we will see this:

The reason is that the page for editing field’s setting use the Name value as a query parameter so the first column that match the Name will be loaded.