C# - Create A String From This Datatable?

I have a datatable with three columns

Id name value value1

I want to create a string from this datatable so that each row in datatable will create two rows name will become one row value 1 will become another row

If name and value1 are similar then include value 1 only otherwise include both name and value1 (this is done)

If name of one row is similar to name in any other row, then add following text infront of both duplicate rows in string

Id is similar to Id

This is what I have written so far:

Public Function GetGazetteer(dataTable As DataTable) As String
Dim processedData = New List(Of String)
Dim rowData = String.Empty[code]....