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