The following will append a number to the saved file when the name exists.

Public Sub SaveAttachments(olItem As MailItem)
'Graham Mayor - http://www.gmayor.com - Last updated - 26 May 2017
Dim olAttach As Attachment
Dim strFname As String
Dim strExt As String
Dim j As Long
Const strSaveFldr As String = "\\Dck-server-02\g\00 Uploads\" 'Folder must exist

    On Error GoTo lbl_Exit
    If olItem.Attachments.Count > 0 Then
        For j = 1 to olItem.Attachments.Count
            Set olAttach = olItem.Attachments(j)
            If Not olAttach.fileName Like "image*.*" Then
                strFname = olAttach.fileName
                strExt = Right(strFname, Len(strFname) - InStrRev(strFname, Chr(46)))
                strFname = FileNameUnique(strSaveFldr, strFname, strExt)
                olAttach.SaveAsFile strSaveFldr & strFname
            End If
        Next j
        olItem.Save
    End If
lbl_Exit:
    Set olAttach = Nothing
    Set olItem = Nothing
    Exit Sub
End Sub

Private Function FileNameUnique(strPath As String, _
                                strFileName As String, _
                                strExtension As String) As String
'An Outlook macro by Graham Mayor
Dim lngF As Long
Dim lngName As Long
    lngF = 1
    lngName = Len(strFileName) - (Len(strExtension) + 1)
    strFileName = Left(strFileName, lngName)
    Do While FileExists(strPath & strFileName & Chr(46) & strExtension) = True
        strFileName = Left(strFileName, lngName) & "(" & lngF & ")"
        lngF = lngF + 1
    Loop
    FileNameUnique = strFileName & Chr(46) & strExtension
lbl_Exit:
    Exit Function
End Function

Private Function FileExists(filespec) As Boolean
'An Outlook macro by Graham Mayor
Dim fso As Object
    Set fso = CreateObject("Scripting.FileSystemObject")
    If fso.FileExists(filespec) Then
        FileExists = True
    Else
        FileExists = False
    End If
lbl_Exit:
    Exit Function
End Function
Test it with

Sub ProcessAttachments()
'An Outlook macro by Graham Mayor
Dim olMsg As MailItem
    On Error Resume Next
    Set olMsg = ActiveExplorer.Selection.Item(1)
    SaveAttachments olMsg
lbl_Exit:
    Exit Sub
End Sub