<p>Magnetic measurements in different thermal-magnetic cycles were carried out on a SmBa₂Cu₃O_7-y single crystal with high critical current density. Two magnetization peaks were simultaneously observed on this strongly pinned sample in different thermal cycles. It was observed that a large and broad maximum on magnetization curves manifested only on a single magnetic field dependent magnetization <i>M-H</i> curve but not on a single zero-field cooling temperature dependent magnetization <i>M-T</i> curve, which was usually defined as fishtail effect (FE). The FE was an irreversible property mainly originated from strong pinning centers. On the other hand, the much smaller magnetization peak manifested only on field cooling <i>M-T</i> curves, which was reversible peak effect (PE). The PE took place at higher temperatures near vortex solid–liquid transition and may be caused by dense and weak pinning centers.</p>