Difference between Chandra and XMM-Newton single-temperature fits to two-temperature component mock spectra vs. the Chandra best-fit temperature. The three colors correspond to different emission measure ratios (EMR) of the cold and hot components, the symbols represent 8 different temperatures of the hot component, while its metallicity is frozen to 0.3 of the solar value and the redshift to 0.05, which corresponds to the mean HIFLUGCS redshift. The temperature and metallicity of the cold component are always fixed to 0.5 and 0.3, respectively. The black curve shows the measured temperature difference between Chandra and XMM-Newton as presented in Table 2.