diff --git a/swh/storage/in_memory.py b/swh/storage/in_memory.py
--- a/swh/storage/in_memory.py
+++ b/swh/storage/in_memory.py
@@ -87,6 +87,7 @@
         for content in contents:
             key = self._content_key(content)
             if key in self._contents:
+                self._objects[key].append(('skipped_content', content['sha1']))
                 continue
             for algorithm in DEFAULT_ALGORITHMS:
                 if content[algorithm] in self._content_indexes[algorithm]:
@@ -103,6 +104,7 @@
                 content_data = self._contents[key].pop('data')
                 self.objstorage.add(content_data, content['sha1'])
 
+
     def content_get(self, ids):
         """Retrieve in bulk contents and their data.
 
@@ -137,6 +139,7 @@
 
             yield {'sha1': obj_id, 'data': data}
 
+
     def content_get_range(self, start, end, limit=1000, db=None, cur=None):
         """Retrieve contents within range [start, end] bound by limit.
 
@@ -1015,11 +1018,11 @@
         raise NotImplementedError('fetch_history_get is deprecated, use '
                                   'origin_visit_get instead.')
 
-    def origin_visit_add(self, origin, date=None, *, ts=None):
+    def origin_visit_add(self, origin_id, date=None, *, ts=None):
         """Add an origin_visit for the origin at date with status 'ongoing'.
 
         Args:
-            origin (int): visited origin's identifier
+            origin_id (int): visited origin's identifier
             date: timestamp of such visit
 
         Returns:
@@ -1039,7 +1042,7 @@
                           DeprecationWarning)
             date = ts
 
-        origin_id = origin  # TODO: rename the argument
+        # origin_id = origin  # TODO: rename the argument
 
         if isinstance(date, str):
             date = dateutil.parser.parse(date)
@@ -1063,6 +1066,9 @@
                 'visit': visit_id,
             }
 
+            key = (origin_id, visit_id)
+            self._objects[key].append(('origin_visit', origin_id))
+
             if self.journal_writer:
                 origin = self.origin_get([{'id': origin_id}])[0]
                 self.journal_writer.write_addition('origin_visit', {
@@ -1070,6 +1076,7 @@
 
         return visit_ret
 
+
     def origin_visit_update(self, origin, visit_id, status=None,
                             metadata=None, snapshot=None):
         """Update an origin_visit's status.
@@ -1370,12 +1377,13 @@
         if key not in self._objects:
             person_id = len(self._persons) + 1
             self._persons.append(dict(person))
-            self._objects[key].append(('person', person_id))
         else:
             person_id = self._objects[key][0][1]
             p = next(self.person_get([person_id]))
             person.update(p.items())
+            # self._objects[key].append(('person', person_id))
         person['id'] = person_id
+        self._objects[key].append(('person', person_id))
 
     @staticmethod
     def _content_key(content):