Significant challenges remain for developing efficient catalysts in an electrochemical multielectron CO2 reduction reaction (CO2RR), which usually suffers from poor activity and selectivity. Motivated by the recent experimental progress in fabricating dual-metal atom catalysts (DMACs) in N-doped graphene materials (graphene-N6V4; N: nitrogen and V: vacancy), we sampled eight types of homonuclear (N6V4-M2, M = Cr, Mn, Fe, Co, Ni, Cu, Pd, and Ag) catalysts and 28 types of heteronuclear (N6V4-M1M2) catalysts to study CO2RR activity via first-principles high-throughput screening. Using stability, activity, and selectivity as indicators along with the broken conventional scaling relationship, N6V4-AgCr was selected as a promising candidate for deep CO2 reduction to methane with a low overpotential of 0.55 V after two screening rounds. Further analysis showed that a frustrated Lewis pair, formed between metal and the para-N, owing to the difference in the electronic arrangement of the d orbitals of various transition metals, caused a difference in the spin polarization of the systems and affected the catalytic performance of each DMAC. Our work not only provides a solid strategy for screening potential catalysts but also demonstrates that their CO2 reduction activities originate from the various atomic and electronic structures of DMACs.