  Different aspects of the Gribov--Glauber approach for calculation of
inclusive pion double charge exchange (DCX) on nuclei are investigated.
Recently we have shown that inelastic rescatterings (IR) with two (and more)
pions in the intermediate states give an important contribution to the process
of DCX at energies above $\sim0.6 GeV$. In this paper we use the one pion
exchange model to study in details amplitudes of two pion production. This
allows us to verify theoretical assumptions made in the previous paper and to
predict cross section for the forward inclusive pion DCX at energies $\ga1
GeV$, where IR dominate over the conventional DCX mechanism of two sequential
single charge exchanges.
