Period spacings in the oscillation spectrum of two HeCB stars, in the red clump (KIC 9815488, top) or the secondary clump (KIC 2583884, bottom). The gray curve indicates the expected period spacings for usual two-cavity mixed modes; the light blue curve corresponds to the three-cavity case. The dark blue curve is derived from the fitted peaks, which are identified with orange ticks. The light gray regions of the oscillation spectra indicate the ranges where radial and quadrupole modes hamper the detection of extra peaks.