For j As Integer = 0 To CInt(adir.Length - 1)
            For jj As Integer = 0 To CInt(bdir.Length - 1)
                If adir(j) = bdir(jj) Then
                    adir(j) = ""
                    bdir(jj) = ""
                End If
            Next jj
        Next j
        count_to_copy = 0
        For jjj As Integer = 0 To 999
            If adir(jjj) <> "" Then
                files_to_copy(count_to_copy) = adir(jjj)
                count_to_copy += 1
            End If
            'If bdir(jjj) <> "" Then
            'files_to_copy(count_to_copy) = bdir(jjj)
            'count_to_copy += 1
            'End If
        Next
        MsgBox("Anzahl zu kopierende Dateien: " & count_to_copy)

Gehe immer vom Guten Willen Anderer aus!