Finally, I can build two versions of Godot Engine from one version of Spine-Godot runtime in the same folder.
Good thing, only one precompiler area of SpineAnimationTrack.cpp needed to be tweaked.
#if VERSION_MAJOR < 4
#include "godot 3.5/editor/editor_node.h"
#else
#include "godot 4.3/editor/editor_node.h"
#endif