Y motors going in opposite direction ?

Total newbie here, when both Y motors are connected and the machine tries to home, the Y motor 2 doesn’t actually allow movement and the machine is clunking back and forth going nowhere ?

If I disconnect Y motor 2 then it runs perfectly on Y motor 1 and homes.

If I disconnect Y motor 1, then it tries to home in the opposite direction away from the Y limit switch … almost like the Y motors are working in opposite directions when they are both connected.

Any help appreciated !