  In this paper, we investigate two hydrogen-poor superluminous supernovae
(SLSNe) iPTF15esb and iPTF13dcc whose light curves (LCs) show significant
deviation from the smooth rise and fall. The LC of iPTF15esb exhibits two peaks
and a post-peak plateau, and furthermore the late-time spectrum of iPTF15esb
shows a strong, broad H$\alpha$ emission line. The early-time LC of iPTF13dcc
shows a long duration bump followed by the second peak. Here we propose an
ejecta-circumstellar medium (CSM) interaction model involving multiple
shells/winds and use it to explain the LCs of iPTF15esb and iPTF13dcc. We find
that the theoretical LCs reproduced by this model can well match the
observations of iPTF15esb and iPTF13dcc. Based on our results, we infer that
the progenitors have undergone multiple violent mass-loss processes before the
SN explosion. In addition, we find that the variation trend of our inferred
densities of the shells is consistent with that predicted by the stellar
mass-loss history before an SN explosion. Further investigations for other
bumpy SLSNe/SNe would shed light on their nature and provide a probe for the
mass-loss history of their progenitors.
