[en] Structural, electrical, and magnetic studies of [(TMTSF)_1-x(TMTTF)_x]₂ReO₄ alloys are reported. They exhibit around x∼0.5 an enhanced charge localization and a strong decrease of the (1/2,1/2,1/2) anion-ordering (AO) transition temperature. The localization enhancement is attributed to a 4k_F order of charge on the sites due to the alternate order of TMTSF and TMTTF molecules. This heteropolar charge distribution is suggested to weaken the 2k_F bond response and thus to depress the AO transition. These properties contrast with those exhibited by the hybrid salt (TMDTDSF)₂ReO₄