On further reflection, you can use the same label e.g.
Code:
Private Sub UserForm_Initialize()
Label1.Picture = LoadPicture("D:\My Pictures\Image_1.bmp")
Label1.Caption = "Image1"
Label1.ForeColor = Label1.BackColor
End Sub
Private Sub CommandButton1_Click()
If Label1.Caption = "Image1" Then
Label1.Picture = LoadPicture("D:\My Pictures\Image_2.bmp")
Label1.Caption = "Image2"
Else
Label1.Picture = LoadPicture("D:\My Pictures\Image_1.bmp")
Label1.Caption = "Image1"
End If
End Sub