  Highly charged relativistic heavy ions have high cross-sections for
two-photon interactions. The photon flux is high enough that two-photon
interactions may be accompanied by additional photonuclear interactions. Except
for the shared impact parameter, these interactions are independent. Additional
interactions like mutual Coulomb excitation are of experimental interest, since
the neutrons from the nuclear dissociation provide a simple, relatively
unbiased trigger.
  We calculate the cross sections, rapidity, mass and transverse momentum
($p_T)$ distributions for exclusive $\gamma\gamma$ production of mesons and
lepton pairs, and for $\gamma\gamma$ reactions accompanied by mutual Coulomb
dissociation. The cross-sections for $\gamma\gamma$ interactions accompanied by
multiple neutron emission ($XnXn$) and single neutron emission ($1n1n$) are
about 1/10 and 1/100 of that for the unaccompanied $\gamma\gamma$ interactions.
We discuss the accuracy with which these cross-sections may be calculated. The
typical $p_T$ of $\gamma\gamma$ final states is several times smaller than for
comparable coherent photonuclear interactions, so $p_T$ may be an effective
tool for separating the two classes of interactions.
