Brillouin spectroscopy and micromagnetic simulations are used to study the propagation of magnetostatic spin waves across adjacent nonidentical magnonic crystals. The characteristics of the spin-wave modes in such a structure depend on the geometry of the slabs, and efficient spin-wave coupling at the magnonic-band-gap frequency can be achieved. This combination of spatial filtering features and spin-wave coupling leads to the realization of a frequency-selective magnonic drop filter, which is expected to extend functionality in spin-wave demultiplexing applications.