Same as Fig. B.1, but for a FEROS observation of the star NGC 4755-003. This is an example of a model fit to a nitrogen-rich evolved star (Hunter et al. 2009). The fit to the He i and most metal lines (including N ii) is poor, indicating a poor choice for the stellar parameters. The derived elemental abundances are thus systematically biased. Moreover, close inspection finds the star to be double-lined. The grey-shaded boxes guide the eye to recognise the double-lined signatures in the most pronounced cases, i.e., the contributions of the two stars to the asymmetric line profiles.