Fix Temperature.h

MarlinKimbra/temperature.h

@@ -130,7 +130,9 @@ FORCE_INLINE void setTargetHotend(const float &celsius, uint8_t extruder) {
 #ifndef SINGLENOZZLE  
   target_temperature[extruder] = celsius;
 #else
-  target_temperature[0] = celsius;
+  if (extruder == active_extruder) {
+    target_temperature[0] = celsius;
+  }
 #endif
 };