  Gaudi, Naber & Sackett pointed out that if an event is caused by a lens
system containing more than two planets, all planets will affect the central
region of the magnification pattern, and thus the existence of the multiple
planets can be inferred by detecting additionally deformed anomalies from
intensive monitoring of high magnification events. Unfortunately, this method
has important limitations in identifying the existence of multiple planets and
determining their parameters due to the degeneracy of the resulting light curve
anomalies from those induced by a single planet and the complexity of multiple
planet lensing models. In this paper, we propose a new channel to search for
multiple planets via microlensing. The method is based on the fact that the
anomalies induced by multiple planets are well approximated by the
superposition of those of the single planet systems where the individual
planet-primary pairs act as independent lens systems. Then, if the source
trajectory passes both of the outer deviation regions induced by the individual
planets, one can unambiguously identify the existence of the multiple planets.
We illustrate that the probability of successively detecting light curve
anomalies induced by two Jovian-mass planets located in the lensing zone
through this channel will be substantial. Since the individual anomalies can be
well modeled by much simpler single planet lensing models, the proposed method
has an important advantage of allowing one to accurately determine the
parameters of the individual planets.
