  Recently M. Kamata and T. Koikawa claimed to obtain the charged version of
the spinning BTZ black hole solution by assuming an (anti-) self dual condition
imposed on the orthonormal basis components of the electric and magnetic
fields. We point out that the Kamata-Koikawa field is not a solution of the
Einstein-Maxwell equations and we find the correct solution of the studied
problem. It is shown that a duality mapping exists among spinning solutions
obtained from electrostatic and magnetostatic fields with the help of the local
transformation $t\longrightarrow t-\omega \theta \theta \longrightarrow \theta
-\omega t.$
