DropDownCheckedListBox Issue - vb.net

Question

Was looking at making a DropDownCheckedListBox for one of my forms. I found a complete source code that was on line.
Public Class DropDownCheckedListBox
Private Const T_DisplayListSize As Integer = 6
Private Const SelectNoneText As String = "(None Selected)"
Private Const SelectAllText As String = "(All Selected)"
Private Const SelectSomeText As String = "(Some Selected...)"
Private Frm As Form
Private Shadows LostFocus As Boolean
Private CodeValue As String
Private T_MustFill As Boolean
Private Shared m_ChkItemsString As String
Public Event DropDown()
Public Shadows Event TextChanged()
Public Sub New()
InitializeComponent()
InitializeNew()
End Sub
Private Sub InitializeNew()
Dim strTemp As String = Nothing
ListSize = T_DisplayListSize
T_DroppedDown = False
T_ListText = ""
T_MustFill = False
txt.Text = strTemp
Checklisbox.Hide()
Frm = New Form
With Frm
.ShowInTaskbar = False
.FormBorderStyle = FormBorderStyle.None
.ControlBox = False
.StartPosition = FormStartPosition.Manual
.TopMost = True
.Location = Checklisbox.Location
.Width = Checklisbox.Width
.Controls.Add(Checklisbox)
End With
SetSize()
End Sub
Private dataList() As String
Public Property Items() As String()
Get
Return dataList
End Get
Set(ByVal value As String())
dataList = value
End Set
End Property
Private ListSize As Integer
Public Property DisplayListSize() As Integer
Get
Return ListSize
End Get
Set(ByVal value As Integer)
ListSize = value
SetList()
End Set
End Property
Private T_DroppedDown As Boolean
Public ReadOnly Property DroppedDown() As Boolean
Get
Return T_DroppedDown
End Get
End Property
Private T_ListText As String
Public ReadOnly Property ListText() As String
Get
Return T_ListText
End Get
End Property
Private Sub ListButtonClick()
Dim strTemp As String
strTemp = T_ListText
If T_DroppedDown Then
T_DroppedDown = False
txt.Text = GetSelectedItems()
Checklisbox.Hide()
Frm.Hide()
txt.Focus()
If Not strTemp = T_ListText Then
RaiseEvent TextChanged()
End If
ElseIf Not LostFocus Then
T_DroppedDown = True
SetSize()
Frm.Show()
Checklisbox.Show()
Checklisbox.Focus()
RaiseEvent DropDown()
End If
LostFocus = False
End Sub
Private Function GetSelectedItems() As String
Dim strLst As String
Dim blnAllSelected As Boolean = False
strLst = ""
With Checklisbox
If .Items.Count > 0 Then
If .CheckedIndices.Count = 0 Then
strLst = SelectNoneText
Else
If .CheckedIndices.Count = .Items.Count Then
strLst = SelectAllText
Else
strLst = .CheckedIndices.Count & " selected" 'SelectSomeText
End If
End If
Else
strLst = SelectNoneText
End If
End With
Return strLst
End Function
'Removed code from this area that was just click, keystrokes events.
'Also Removed resize code.
Public Event SelectedIndexChanged(ByVal sender As DropDownCheckedListBox)
Public Shared Function GetItemsNameString(ByVal tempListBox As CheckedListBox) As String
m_ChkItemsString = ""
Try
If tempListBox.CheckedItems.Count > 0 Then
Dim tempItem As Object
For Each tempItem In tempListBox.CheckedItems
m_ChkItemsString = m_ChkItemsString & "," & tempItem.ToString()
Next
End If
m_ChkItemsString = m_ChkItemsString.Trim().Substring(1, m_ChkItemsString.Length - 1)
Catch ex As Exception
End Try
Return m_ChkItemsString
End Function
Public Sub setText(ByVal chklist As CheckedListBox)
If chklist.Items.Count > 0 Then
If chklist.CheckedIndices.Count = chklist.Items.Count Then
txt.Text = SelectAllText
Exit Sub
End If
If chklist.CheckedIndices.Count > 0 Then
txt.Text = chklist.CheckedIndices.Count & " selected"
ElseIf chklist.CheckedIndices.Count = 0 Then
txt.Text = SelectNoneText
End If
Else
txt.Text = SelectNoneText
End If
End Sub
Private Sub bChkLstBox_Load(ByVal sender As System.Object, ByVal e As System.EventArgs)
If Not dataList Is Nothing Then
If dataList.GetUpperBound(0) > 0 Then
For i As Integer = 0 To dataList.GetUpperBound(0)
If Not dataList(i) Is Nothing Then
Checklisbox.Items.Add(dataList(i))
End If
Next
End If
End If
End Sub
'Removed mouse events
End Class
This code works but I discovered a problem.
When I select items 1, 2, and 3 from the list and tell it to display the items in an list box I come up with the following: 1, 1, 2, 1, 2, 3.
I am still going over the code trying to figure it out but more experience individuals advice would be helpful.
Thanks in advance, and Apologies for the long code.
Edit:
Code to send items to Listbox
Dim Litems As New List(Of String)
ListBox1.Items.Clear()
Litems.Clear()
For Each I As String In DropDownCheckedListBox1.Checklisbox.CheckedItems
Litems.Add(I)
ListBox1.Items.AddRange(Litems.ToArray)
next

Answer 1

Move your AddRange line to outside the loop, otherwise, you keep re-adding the contents of your list to the ListBox:
Dim Litems As New List(Of String)
ListBox1.Items.Clear()
Litems.Clear()
For Each I As String In DropDownCheckedListBox1.Checklisbox.CheckedItems
Litems.Add(I)
next
ListBox1.Items.AddRange(Litems.ToArray)