Only store active source when it differs.

src/service.py

@@ -191,9 +191,10 @@ class ApiService():
             source_number (Integer): Number of the engine
         """
         if self.active_source > 0:
-            self.active_source = source_number
-            activity_log = ActivityLog(active_source)
-            activity_log.save()
+            if self.active_source != source_number:
+                self.active_source = source_number
+                activity_log = ActivityLog(active_source)
+                activity_log.save()
 
 
     def get_active_source(self):