IMPEDIR QUE ITEM NAO SE REPITA NA LISTVIEW

HashSet<int> Item = new HashSet<int>;

Public Class Paciente
	Public Property CNS() As String
		Get
			Return m_CNS
		End Get
		Set
			m_CNS = Value
		End Set
	End Property
	Private m_CNS As String
	Public Property Nome() As String
		Get
			Return m_Nome
		End Get
		Set
			m_Nome = Value
		End Set
	End Property
	Private m_Nome As String
	Public Property HIV() As String
		Get
			Return m_HIV
		End Get
		Set
			m_HIV = Value
		End Set
	End Property
	Private m_HIV As String
	Public Function BuscaPacientesPlanilha(CaminhoPlanilha As String, Celula As String) As List(Of Paciente)
		Dim _return As List(Of Paciente) = Nothing
		Dim connectionString As String = [Ô]Provider = Microsoft.ACE.OLEDB.12.0; Data source=[Ô] & CaminhoPlanilha & [Ô];Extended Properties=[Ô][Ô]Excel 12.0;HDR= yes;[Ô][Ô][Ô]
		Dim cn As New OleDbConnection(connectionString)
		cn.Open()
		Dim cmd As New OleDbCommand([Ô]Select [Num do Cartão SISPRENATAL],[Nome da Usuária] from [[Ô] & CaminhoPlanilha & [Ô]$] [Ô])
		Dim dr As OleDbDataReader = cmd.ExecuteReader()
		If dr.HasRows Then
			_return = New List(Of Paciente)()
			While dr.Read()
				_return.Add(New Paciente() With { _
					Key .CNS = dr.GetString(0), _
					Key .Nome = dr.GetString(1) _
				})
			End While
		End If
		Return _return

	End Function
End Class

Dim lista As List(Of Paciente) = New Paciente.BuscaPacientesPlanilha(txtCaminho.Text, txtPlanilha.Text).ToList()
Dim listaFiltrada As List(Of Paciente) = lista.GroupBy(Function(paciente) paciente.CNS).[Select](Function(group) group.First()).ToList()

For Each paciente In listaFiltrada
    Dim lvi2 As New ListViewItem()
    For i2 As Integer = 1 To dt2.Columns.Count - 1
        lvi2.Text = paciente.CNS.ToString()
        lvi2.SubItems.Add(paciente.Nome.ToString())
    Next
    ListView2.Items.Add(lvi2)
Next paciente