Script Task To Compare File From FTP With File On Local Archive Behaved Strangely!

In my script task I have the following code. The task I'm trying to accomplish is:
If the filename on FTP can be found in the local archive folder of e: drive then show message "FileAlreadyThere" (I will ultimatley change it to do nothing); if the filename on FTP cannot be found in the local archive folder of e: drive then transfer the file to the local package folder on d: drive.

While the script task is executing I was watching it closely, but the problem i saw is that:
If some files on FTP are already in local archive folder and some are not, then it the files which are already in the archive folder are dumped to the package folder; then after that the files which are not in the archive folder are then dumped to the package folder. But I only want the new files on FTP to be transferred to the package folder for further processing.

Then after this is finished, I saw all the files in the package folder are refreshed one after another, after the first round of refresh the second round starts, after the second round finishes it then stopped. I saw it refreshes itself because the 'Date Modified' of the file changes. And I saw the script task turned green.

I don't see how the code below produced this result. Something is wrong in the logic of the loop? Anyone has any idea why it's behaving the way it is now? And how to change the code to accomplish what I want? Thanks a lot!!

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Imports System
Imports System.IO
Imports System.Data
Imports System.Math
Imports Microsoft.SqlServer.Dts.Runtime
Public Class ScriptMain
Public Sub Main()
Dim cm As ConnectionManager = Dts.Connections.Add("FTP")
cm.Properties("ServerName").SetValue(cm, "ftp2.name.com")
cm.Properties("ServerUserName").SetValue(cm, "username")
cm.Properties("ServerPassword").SetValue(cm, "password")
cm.Properties("ServerPort").SetValue(cm, "21")
cm.Properties("Timeout").SetValue(cm, "0")
cm.Properties("ChunkSize").SetValue(cm, "1000") '1000 kb
cm.Properties("Retries").SetValue(cm, "1")
Dim ftp As FtpClientConnection = New FtpClientConnection(cm.AcquireConnection(Nothing))
ftp.Connect()
ftp.SetWorkingDirectory("/directory")
Dim fileNames() As String
Dim folderNames() As String
ftp.GetListing(folderNames, fileNames)
If fileNames Is Nothing Then
MsgBox("NoFileOnFTP")
Else
Dim fileName As String
For Each fileName In fileNames
If File.Exists("c: emp" + fileName) Then
MsgBox("FileAlreadyThere")
Else
ftp.ReceiveFiles(fileNames, "c: emp", True, True)
End If
Next
End If

ftp.Close()
End Sub
End Class