  This paper is devoted to the leading twist exclusive bottomonia decays with
double charmonium in the final state. Using models of the twist-2 charmonia
distribution amplitudes the widths of these decays are calculated within light
cone formalism. In addition, the processes under consideration are studied
within nonrelativistic QCD. In our analysis we have found that the production
of some of the $P$-wave charmonia mesons with $L_z \neq 0$ is allowed already
at the leading twist approximation. This means that the selection rules which
predict the suppression of such decays are violated. The mechanism which lies
behind this violation is discussed.
