Coherent dissipative structures known as platicons can be reliably generated in photonic molecules, resulting in deterministic and reproducible microcombs derived from a continuous-wave pump. However, the supermode spectrum of standard photonic molecules displays numerous avoided mode crossings, distorting the spectral envelope of platicon microcombs. Here, we obtain a platicon microcomb using a photonic molecule configuration based on two coupled microcavities, whose size differs by an order of magnitude. This results in an engineered microcomb spectrum that closely resembles the one generated in an ideal single microresonator with just one frequency mode shift. We observe the coupling between the repetition rate of the platicon microcomb with the frequency of the pump laser, an effect originating from the dispersive-wave recoil induced by mode crossings. Using two identical platicon microcombs, we make use of such coupling to realize dual-comb interferometry. These results contribute to understanding dissipative structures in normal-dispersion microresonators and offer an alternative to applications such as spectroscopy and metrology.