Make Y_DUAL_STEPPER_DRIVERS disabled by default

Marlin/Configuration_adv.h

 #endif
 
 // Same again but for Y Axis.
-#define Y_DUAL_STEPPER_DRIVERS
+//#define Y_DUAL_STEPPER_DRIVERS
 
 // Define if the two Y drives need to rotate in opposite directions
 #define INVERT_Y2_VS_Y_DIR true