  Resolved ALMA and VLA observations indicate the existence of two dust traps
in the protoplanetary disc MWC 758. By means of 2D gas+dust hydrodynamical
simulations post-processed with 3D dust radiative transfer calculations, we
show that the spirals in scattered light, the eccentric, asymmetric ring and
the crescent-shaped structure in the (sub)millimetre can all be caused by two
giant planets: a 1.5-Jupiter mass planet at 35 au (inside the spirals) and a
5-Jupiter mass planet at 140 au (outside the spirals). The outer planet forms a
dust-trapping vortex at the inner edge of its gap (at ~85 au), and the
continuum emission of this dust trap reproduces the ALMA and VLA observations
well. The outer planet triggers several spiral arms which are similar to those
observed in polarised scattered light. The inner planet also forms a vortex at
the outer edge of its gap (at ~50 au), but it decays faster than the vortex
induced by the outer planet, as a result of the disc's turbulent viscosity. The
vortex decay can explain the eccentric inner ring seen with ALMA as well as the
low signal and larger azimuthal spread of this dust trap in VLA observations.
Finding the thermal and kinematic signatures of both giant planets could verify
the proposed scenario.
