  In the present work we examine the statics and dynamics of multiple parallel
dark soliton stripes in a two-dimensional Bose-Einstein condensate. Our
principal goal is to study the effect of the interaction between the stripes on
the transverse instability of the individual stripes. We use a recently
developed adiabatic invariant formulation to derive a quasi-analytical
prediction for the stripe equilibrium position and for the Bogoliubov-de Gennes
spectrum of excitations of stationary stripes. The cases of two-, three- and
four-stripe states are studied in detail. We subsequently test our predictions
against numerical simulations of the full two-dimensional Gross-Pitaevskii
equation. We find that the number of unstable eigenmodes increases as the
number of stripes increases due to (unstable) relative motions between the
stripes. Their corresponding growth rates do not significantly change, although
for large chemical potentials, the larger the stripe number, the larger the
maximal instability growth rate. The instability induced dynamics of multiple
stripe states and their decay into vortices are also investigated.
