#define XAXIS_STEPS_PER_MM 91.4286

#define X_MAX_POS 100

using #define Z_MAX_LENGTH 50 (instead of 80) is better. this does not going to much down.

-I set #define Z_PROBE_START_SCRIPT "G28\nG30 P0 H0"

#define Z_MAX_LENGTH 80

#define CONFIGURATION_H

Don´t ask me why but that was the needed hint! #define RFSERIAL Serial and #define BLUETOOTH_SERIAL 101 was set already so i tied to use the Native USB Port at the Due. This worked! So now, still the

#define RFSERIAL Serial

#define FEATURE_SERVO 1

#define UI_DISPLAY_RS_PIN 44 //CS

#define LAZY_DUAL_X_AXIS 1

#define MULTI_ZENDSTOP_HOMING 0

#define UI_TEXT_MAINPAGE6_1_EN "\xa %ec/%Ec\xb0 X:%x0"

#define MOVE_X_WHEN_HOMED 0

#define UI_DELAYPERCHAR 50

#define EXT2_STEP_PIN ORIG_E2_STEP_PIN

#define ST7920_DELAY_1 DELAY_NS(63)

#define PRINTJOB_TIMER_AUTOSTART

before each #define MACRONAME to remove the old definition without warning.

#define EXT0_TEMPSENSOR_TYPE         1