Private Sub Command1_Click()
 
sFilter1 = "FilterText"
sFilter2 = "FiltertextXY"
...
...
...
 
If txtText.Text <> sFilter1 Then
  If txtText.Text <> sFilter2 Then
    If txtText.Text <> sFilter3 Then
      If txtText.Text <> sFilter4 Then
        If txtText.Text <> sFilter5 Then
            List1.AddItem txtText.Text
        End If
      End If
    End If
  End If
End If
 
End Sub

Private Sub Command1_Click()
 
Dim k As Integer
 
If Not Text1.Text = "" Then
 
        For k = 0 To lstFilter.ListCount
            If LCase(lstFilter.List(k)) = LCase(Text1.Text) Then
 
                Exit Sub
 
            End If
        Next
            List1.AddItem Text1.Text
 
End If
 
End Sub