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/Program.vb

Imports System
Imports System.Collections.Generic
Imports System.Linq
				
Public Module Module1
	Public Class Thing
		Private _name As String = Nothing
		Public Property Name As String
			Get
				Return _name
			End Get
			Set(ByVal value As String)
				_name = value
			End Set
		End Property
		
		Private _serviceGroup As Integer = 0
		Public Property ServiceGroup As String
			Get
				Return _serviceGroup
			End Get
			Set(ByVal value As String)
				_serviceGroup = value
			End Set
		End Property		
		
		Public Sub New(name as String, serviceGroup as String)
			_name = name
			_serviceGroup = serviceGroup
		End Sub
	End Class	
	
	Public Sub Main()
		Dim unique1 as Thing = new Thing("test", 1)
		Dim unique2 as Thing = new Thing("test1", 1)
		Dim unique3 as Thing = new Thing("test", 2)
		Dim dup1 as Thing = new Thing("test", 1)
		Dim dup2 as Thing = new Thing("test", 1)
	
		Dim things as Thing() = {
			unique1,
			unique2,
			unique3,
			dup1,
			dup2
		}
	
		Dim duplicates As List(Of Thing) = 
			things.
				GroupBy(Function(thing) New With {Key .Name = thing.Name, Key .ServiceGroup = thing.ServiceGroup }).
				Where(Function(group) group.Count() > 1).
				SelectMany(Function(group) group.ToList).
				ToList()
			
		For Each thing as Thing in duplicates
			Console.WriteLine("{0}:{1}", thing.Name, thing.ServiceGroup)
		Next
	End Sub
End Module