  Some noncommutative (NC) theories posses a certain type of dualities that are
implicitly built within their structure. In this paper we establish still
another example of this kind. More precisely, we show that the noncommutative
U(1) gauge theory coupled to a NC scalar field and to a classical geometry of
the Reissner Nordstrom (RN) type is completely equivalent at the level of
equations of motion to the commutative U(1) gauge theory coupled to a
commutative scalar field and to a classical geometry background, different from
the starting RN background. The new (effective) metric is obtained from the RN
metric by switching on an additional nonvanishing r-phi component. Using this
duality between two theories and physical systems they describe, we formulate
an effective approach to studying a dynamics of spin 1/2 fields on the curved
background of RN type with an abiding noncommutative structure. As opposed to
that, we also study the dynamics of spin 1/2 fields in a more formal way, by
studying the semiclassical theory which describes the NC U(1) gauge field
coupled with NC spin 1/2 field and also with gravity which is however treated
classically. Upon utilising the Seiberg Witten map in order to write the NC
spinor and NC gauge fields in terms of their corresponding commutative degrees
of freedom, we find that the equation of motion for the fermion field obtained
within the formal approach exactly coincides with the equation of motion
obtained within the effective approach that utilises noncommutative duality. We
then use these results to analyze the problem of stability of solutions of the
equations of motion and the associated issue of superradiance, as related to
fermions in RN spacetime with an allpervasive noncommutative structure.
