How to add uniq files to playlist in itunes

I have a function in VB. that copies all files in a given folder to the itunes playlist.

The below function creats a playlist “puja” in itunes and
copies all songs from the folder c:Pujafolder to puja.

Public Function CopyAudioToiTunes()

PlaylistName = “Puja”
'Set iTunesApp = CreateObject(“iTunes.Application”)
Set iTunesApp = New iTunesApp
Dim Albumplaylist
Set Albumplaylist = Nothing
Set Albumplaylist = iTunesApp.LibrarySource.Playlists.ItemByName(PlaylistName)
If Albumplaylist Is Nothing Then
Set Albumplaylist = iTunesApp.CreatePlaylist(PlaylistName)
MsgBox “Creating new Playlist” & Albumplaylist.Name
End If
Dim AudioFilesArray(0) As String
AudioFilesArray(0) = “c:Pujafolder”

Albumplaylist.AddFiles (AudioFilesArray)
MsgBox (“Created playlists and added audio files to itunes.”)

End Function

The problem is everytime i add new audio files to the folder Pujafolder and call this function it copies all the files (the old and the new ones) . Is there a way to only copy those files which don’t exist in the current playlist.

Thanks in advance