  As revealed by its peculiar Kepler light curve, the enigmatic star KIC
8462852 undergoes short and deep flux dimmings at a priori unrelated epochs. It
presents nonetheless all other characteristics of a quiet 1 Gyr old F3V star.
These dimmings resemble the absorption features expected for the transit of
dust cometary tails. The exocomet scenario is therefore most commonly
advocated. We reanalyzed the Kepler data and extracted a new high-quality light
curve to allow for the search of shallow signature of single or a few
exocomets. We discovered that among the 22 flux dimming events that we
identified, two events present a striking similarity. These events occurred
928.25 days apart, lasted for 4.4 days with a drop of the star brightness by
1000 ppm. We show that the light curve of these events is well explained by the
occultation of the star by a giant ring system, or the transit of a string of
half a dozen of exocomets with a typical dust production rate of 10$^5$-10$^6$
kg/s. Assuming that these two similar events are related to the transit of the
same object, we derive a period of 928.25 days. The following transit was
expected in March 2017 but bad weather prohibited us to detect it from
ground-based spectroscopy. We predict that the next event will occur from the
3rd to the 8th of October 2019.
