  More than 40 years after the first discussion, it was recently reported the
detection of a self-lensing phenomenon within a binary system where the
brightness of a background star is magnified by its foreground companion. It is
expected that the number of self-lensing binary detections will be increased in
a wealth of data from current and future survey experiments. In this paper, we
introduce a degeneracy in the interpretation of self-lensing light curves. The
degeneracy is intrinsic to self-lensing binaries for which both magnification
by lensing and de-magnification by occultation occur simultaneously and is
caused by the difficulty in separating the contribution of the lensing-induced
magnification from the observed light curve. We demonstrate the severity of the
degeneracy by presenting example self-lensing light curves suffering from the
degeneracy. We also present the relation between the lensing parameters of the
degenerate solutions. The degeneracy would pose as an important obstacle in
accurately determine self-lensing parameters and thus to characterize binaries.
