Merge branch '309-some-documentations-are-duplicated-in-coursebook' into 'master'

Resolve "Some documentations are duplicated in coursebook"

Closes #309

See merge request !389

aleksis/apps/alsijil/models.py

@@ -557,7 +557,9 @@ class Documentation(CalendarEvent):
             event_reference_obj = event["REFERENCE_OBJECT"]
             existing_documentations_event = filter(
                 lambda d: (
-                    d.datetime_start == event["DTSTART"].dt and d.datetime_end == event["DTEND"].dt
+                    d.datetime_start == event["DTSTART"].dt
+                    and d.datetime_end == event["DTEND"].dt
+                    and d.amends.id == event_reference_obj.id
                 ),
                 existing_documentations,
             )