Comparison of the magnesium triplet line strength between the two stars with similar stellar parameters SDSS J135046 and SDSSJ104531. The flux difference between the two stars is plotted as a grey line on the upper part of the figure. For clarity, this difference has been shifted up by 1.15. The lower part of the plot shows the similar shape of the H β line for both stars. The difference in [Fe/H] between these two stars is on the order of 0.4 dex. Setting the two stars at the same metallicity [Fe/H] = −3.0 dex would increase the difference in the [Mg/Fe] ratio.