The KL2,3 (alpha)12-lines of 19K, the L3M4,5 (alpha)12-lines of 48Cd, and the M5N6,7 (alpha)12-lines of 92U are lines of comparable energy in the region of approximately 3 keV. In none of these cases were we able to resolve the three doublets when recording the spectra in first order Bragg spectrometry using a PET crystal as the dispersing element. In order to enhance the resolving power of the spectrometer, the three spectra were recorded in second order reflection, thereby transferring the lines into another spectral region dominated by X-ray quanta of half the energy. In order to achieve high net peak intensities as well as a high peak-to-background ratio and, consequently, a high level of detection capability, the discriminator settings should be optimized quite carefully. In this manner, we were able to resolve the three alpha doublets and estimate alpha2/alpha1 intensity ratios. Unfortunately, current monographs, e.g. by Goldstein et al., do not contain any indications about the rational use of high order spectrometry. Only a few rather old monographs contain some hints in this regard.