A welding or additive manufacturing wire drive system, comprising a single welding wire spool (102, 110) having a first welding wire and a second welding wire, wherein the first and second welding wires (E1, E2) are wound on the single wire spool (102, 110); a first drive roll; a second drive roll, wherein one or both of the first drive roll and the second drive roll has a circumferential groove; the wire drive system being characterised by: the circumferential groove comprises a first sidewall portion, a second sidewall portion and a groove base (141, 152, 153) extending between the sidewalls portions (137, 139) and is designed to receive the two welding wires (E1, E2), wherein the system is configured that the first welding wire is drawn from the single welding wire spool (102, 110), located between the first drive roll and the second drive roll in the circumferential groove; and wherein the system is configured that the second welding wire is drawn simultaneously with the first welding wire from the single welding wire spool (102, 110), located between the first drive roll and the second drive roll in the circumferential groove, wherein system is configured that the first welding wire contacts the second welding wire between the first drive roll and the second drive roll, and wherein the system is configured that the first welding wire further contacts the first sidewall portion (137, 147, 150) of the circumferential groove, and wherein the system is configured that the second welding wire further contacts the second sidewall portion (139, 149, 150) of the circumferential groove, and wherein the system is configured that both of the first welding wire and the second welding wire are radially offset from a central portion of the circumferential groove. a single welding wire spool (102, 110) having a first welding wire and a second welding wire, wherein the first and second welding wires (E1, E2) are wound on the single wire spool (102, 110); a first drive roll; a second drive roll, wherein one or both of the first drive roll and the second drive roll has a circumferential groove; the wire drive system being characterised by: the circumferential groove comprises a first sidewall portion, a second sidewall portion and a groove base (141, 152, 153) extending between the sidewalls portions (137, 139) and is designed to receive the two welding wires (E1, E2), wherein the system is configured that the first welding wire is drawn from the single welding wire spool (102, 110), located between the first drive roll and the second drive roll in the circumferential groove; and wherein the system is configured that the second welding wire is drawn simultaneously with the first welding wire from the single welding wire spool (102, 110), located between the first drive roll and the second drive roll in the circumferential groove, wherein system is configured that the first welding wire contacts the second welding wire between the first drive roll and the second drive roll, and wherein the system is configured that the first welding wire further contacts the first sidewall portion (137, 147, 150) of the circumferential groove, and wherein the system is configured that the second welding wire further contacts the second sidewall portion (139, 149, 150) of the circumferential groove, and wherein the system is configured that both of the first welding wire and the second welding wire are radially offset from a central portion of the circumferential groove. the circumferential groove comprises a first sidewall portion, a second sidewall portion and a groove base (141, 152, 153) extending between the sidewalls portions (137, 139) and is designed to receive the two welding wires (E1, E2), wherein the system is configured that the first welding wire is drawn from the single welding wire spool (102, 110), located between the first drive roll and the second drive roll in the circumferential groove; and wherein the system is configured that the second welding wire is drawn simultaneously with the first welding wire from the single welding wire spool (102, 110), located between the first drive roll and the second drive roll in the circumferential groove, wherein system is configured that the first welding wire contacts the second welding wire between the first drive roll and the second drive roll, and wherein the system is configured that the first welding wire further contacts the first sidewall portion (137, 147, 150) of the circumferential groove, and wherein the system is configured that the second welding wire further contacts the second sidewall portion (139, 149, 150) of the circumferential groove, and wherein the system is configured that both of the first welding wire and the second welding wire are radially offset from a central portion of the circumferential groove.