Fix stepper direction macros, multi-nozzle scope (#13569)

Marlin/src/module/motion.cpp

 #if HAS_DUPLICATION_MODE
   bool extruder_duplication_enabled,
        mirrored_duplication_mode;
-#endif
-
-#if ENABLED(MULTI_NOZZLE_DUPLICATION) && HOTENDS > 2
-  uint8_t duplication_e_mask; // = 0
+  #if ENABLED(MULTI_NOZZLE_DUPLICATION)
+    uint8_t duplication_e_mask; // = 0
+  #endif
 #endif
 
 #if ENABLED(DUAL_X_CARRIAGE)

Marlin/src/module/motion.h

 #if HAS_DUPLICATION_MODE
   extern bool extruder_duplication_enabled,       // Used in Dual X mode 2
               mirrored_duplication_mode;          // Used in Dual X mode 3
-#endif
-
-#if ENABLED(MULTI_NOZZLE_DUPLICATION) && HOTENDS > 2
-  uint8_t duplication_e_mask;
+  #if ENABLED(MULTI_NOZZLE_DUPLICATION)
+    extern uint8_t duplication_e_mask;
+  #endif
 #endif
 
 /**

Marlin/src/module/stepper_indirection.h

     #define    _REV_E_DIR(E)   do{ if (E == 0) { E0_DIR_WRITE( INVERT_E0_DIR); } else { E1_DIR_WRITE( INVERT_E1_DIR); } }while(0)
   #endif
 
-  #if EITHER(DUAL_X_CARRIAGE, MULTI_NOZZLE_DUPLICATION)
+  #if HAS_DUPLICATION_MODE
+
+    #if ENABLED(MULTI_NOZZLE_DUPLICATION)
+      #define _DUPE(N,T,V)  do{ if (TEST(duplication_e_mask, N)) E##N##_##T##_WRITE(V); }while(0)
+    #else
+      #define _DUPE(N,T,V)  E##N##_##T##_WRITE(V)
+    #endif
+
+    #define NDIR(N) _DUPE(N,DIR,!INVERT_E##N##_DIR)
+    #define RDIR(N) _DUPE(N,DIR, INVERT_E##N##_DIR)
 
-    #define NDIR(N) _DUPE(DIR,!INVERT_E##N##_DIR)
-    #define RDIR(N) _DUPE(DIR, INVERT_E##N##_DIR)
     #define E_STEP_WRITE(E,V) do{ if (extruder_duplication_enabled) { DUPE(STEP,V); } else _E_STEP_WRITE(E,V); }while(0)
 
     #if E_STEPPERS > 2
-      #define _DUPE(N,T,V)    do{ if (duplication_e_mask <= (N)) E##N##_##T##_WRITE(V); }while(0)
       #if E_STEPPERS > 5
         #define DUPE(T,V)     do{ _DUPE(0,T,V); _DUPE(1,T,V); _DUPE(2,T,V); _DUPE(3,T,V); _DUPE(4,T,V); _DUPE(5,T,V); }while(0)
         #define NORM_E_DIR(E) do{ if (extruder_duplication_enabled) { NDIR(0); NDIR(1); NDIR(2); NDIR(3); NDIR(4); NDIR(5); } else _NORM_E_DIR(E); }while(0)
         #define REV_E_DIR(E)  do{ if (extruder_duplication_enabled) { RDIR(0); RDIR(1); RDIR(2); } else  _REV_E_DIR(E); }while(0)
       #endif
     #else
-      #define _DUPE(T,V)    do{ E0_##T##_WRITE(V); E1_##T##_WRITE(V); }while(0)
-      #define DUPE(T,V)  _DUPE(T,V)
+      #define DUPE(T,V)     do{ _DUPE(0,T,V); _DUPE(1,T,V); } while(0)
       #define NORM_E_DIR(E) do{ if (extruder_duplication_enabled) { NDIR(0); NDIR(1); } else _NORM_E_DIR(E); }while(0)
       #define REV_E_DIR(E)  do{ if (extruder_duplication_enabled) { RDIR(0); RDIR(1); } else  _REV_E_DIR(E); }while(0)
     #endif