Diploid cells contain two chromosomes of each type. At the end of telophase, the daughter cells are identical to the original parent cell - hence diploid.  However, the chromosomes are no longer duplicated (as they were at the beginning of mitosis). If this had been meiosis, telophase would have been noted as telophase I or telophase II.  At the end of telophase I, each cell contains one duplicated chromosome (chromosomes composed of two sister chromatids), and at the end of telophase II, each cell contains one chromosome of each type which is no longer duplicated.