Planetary accretion rates (top row) and masses (bottom row) as a function of time for different α-viscosities. Here the planets are fixed in a 3:1 period ratio: the inner planet is shown in red and the outer one in blue. As in Bergez-Casalou et al. (2020), the accretion rates slightly increase with increasing viscosity. The oscillations in the accretion rate at low viscosities are due to the presence of vortices. The inner and outer planets display similar accretion rates, leading to similar planet masses.