By designing an appropriate defect potential in a nonresonantly pumped exciton-polariton condensate, the polariton dyad consisting of two spatially separated condensates with phase locking can be realized. We use the phase coupling of the polariton dyad to investigate the existence of both dark and anti-dark solitons in the condensates. Surprisingly, these dissipative solitons appear to be stable and are not affected by the noise both from the initial condition and from the propagation. We show that these stable solitons are transformed from a spontaneously created metastable states by choosing the state with the highest particle number.