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The one-quasiparticle random-phase approximation (one-QRPA) method is used to describe simultaneously both double-¥â-decay modes, giving special attention to the partial restoration of spin-isospin SU(4) symmetry. To implement this restoration and to fix the model parameters, we resort to the energetics of Gamow-Teller resonances and to the minima of the single-¥â +-decay strengths. This makes the theory predictive regarding the ¥â¥â2¥í decay, producing the 2¥í moments in 48Ca, 76Ge, 82Se, 96Zr, 100Mo, 128,130Te, and 150Nd, that are of thesame order of magnitude as the experimental ones; however, the agreement with ¥â¥â2¥í data is only modest. To include contributions coming from induced nuclear weak currents, we extend the ¥â¥â0¥í-decay formalism employed previously in C. Barbero et al., Nucl. Phys. A 628, 170 (1998), which is based on the Fourier-Bessel expansion. The numerical results for the ¥â¥â0¥í moments in the above mentioned nuclei are similar to those obtained in other theoretical studies although smaller on average by ¡40%.We attribute this difference basically to the one-QRPA method, employed here for the first time, instead of the currently used two-QRPA method. The difference is partially due also to the way of carrying out the restoration of the spin-isospin symmetry. It is hard to say which is the best way to make this restoration, since the ¥â¥â0¥í moments are not experimentally measurable. The recipe proposed here is based on physically robust arguments. The numerical uncertainties in the ¥â¥â moments, relatedto (i) their strong dependence on the residual interaction in the particle-particle channel when evaluated within the QRPA, and (ii) lack of proper knowledge of single-particle energies, have been quantified. It is concluded that the partial restoration of the SU(4) symmetry, generated by the residual interaction, is crucial in the description of the ¥â¥â decays, regardless of the nuclear model used.