  In this paper, I study the topological excitations in a pairing state in
double layer systems at Landau level filling factor $\nu=1/2$ in the presence
of disorders. Due to mismatches between single particle wave functions of
composite Fermions in different layers, the sensitivity of the Chern number of
the pairing state, with respect to changes of impurities, is infinity.
Consequently, Goldstone mode in this pairing state is strongly damped at low
temperature. It is argued that this leads to a unique temperature dependence of
the drag resistance at low temperature.
