machines/systems/flexibot/docs/marlin/_gcode/M666-dual.md

tag	title	brief	author	group	requires	codes	parameters	examples
m0666b	Set dual endstop offsets	Set dual endstop offsets	ManuelMcLure	calibration	(X|Y|Z)_DUAL_ENDSTOPS	M666	tag optional description values X true Offset for the X axis endstops tag type adj float tag optional description values Y true Offset for the Y axis endstops tag type adj float tag optional description values Z true Offset for the Z axis endstops tag type adj float

Use the M666 command to adjust the offsets for dual (or multiple) endstops.