Here the 1892 RLDS edition omitted the repeated auxiliary verb did in the conjoined verb phrase “and did devour”. The 1908 RLDS edition restored the did to the RLDS text. Either reading is theoretically possible here, so we follow the earliest text with the repeated did. See under Ether 2:2 for an example of a conjoined verb phrase where the did was not repeated in the original text.
Summary: Maintain the repeated did in Ether 9:34: “the people did follow the course of the beasts and did devour the carcasses of them which fell by the way” (the reading of the earliest text).