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
@@ -831,13 +831,15 @@
         return all_visits
 
     def _origin_visit_status_add_one(self, visit_status: OriginVisitStatus) -> None:
-        """Add an origin visit status without checks.
+        """Add an origin visit status without checks. If already present, do nothing.
 
         """
         self.journal_writer.origin_visit_status_add([visit_status])
         visit_key = (visit_status.origin, visit_status.visit)
         self._origin_visit_statuses.setdefault(visit_key, [])
-        self._origin_visit_statuses[visit_key].append(visit_status)
+        visit_statuses = self._origin_visit_statuses[visit_key]
+        if visit_status not in visit_statuses:
+            visit_statuses.append(visit_status)
 
     def origin_visit_status_add(
         self, visit_statuses: Iterable[OriginVisitStatus],
diff --git a/swh/storage/tests/test_storage.py b/swh/storage/tests/test_storage.py
--- a/swh/storage/tests/test_storage.py
+++ b/swh/storage/tests/test_storage.py
@@ -1748,33 +1748,38 @@
         with pytest.raises(StorageArgumentException, match="Unknown origin"):
             swh_storage.origin_visit_status_add([visit_status1])
 
+        objects = list(swh_storage.journal_writer.journal.objects)
+        assert not objects
+
     def test_origin_visit_status_add(self, swh_storage):
         """Correct origin visit statuses should add a new visit status
 
         """
-        origin_url = swh_storage.origin_add_one(data.origin2)
+        origin1 = Origin.from_dict(data.origin2)
+        origin2 = Origin(url="new-origin")
+        swh_storage.origin_add([origin1, origin2])
+
         visit1 = OriginVisit(
-            origin=origin_url,
+            origin=origin1.url,
             date=data.date_visit1,
             type=data.type_visit1,
             status="ongoing",
             snapshot=None,
         )
-        origin_url2 = swh_storage.origin_add_one({"url": "new-origin"})
         visit2 = OriginVisit(
-            origin=origin_url2,
+            origin=origin2.url,
             date=data.date_visit2,
             type=data.type_visit2,
             status="ongoing",
             snapshot=None,
         )
-        origin_visit1, origin_visit2 = swh_storage.origin_visit_add([visit1, visit2])
+        ov1, ov2 = swh_storage.origin_visit_add([visit1, visit2])
 
         snapshot_id = data.snapshot["id"]
         date_visit_now = now()
         visit_status1 = OriginVisitStatus(
-            origin=origin_visit1.origin,
-            visit=origin_visit1.visit,
+            origin=ov1.origin,
+            visit=ov1.visit,
             date=date_visit_now,
             status="full",
             snapshot=snapshot_id,
@@ -1782,8 +1787,8 @@
 
         date_visit_now = now()
         visit_status2 = OriginVisitStatus(
-            origin=origin_visit2.origin,
-            visit=origin_visit2.visit,
+            origin=ov2.origin,
+            visit=ov2.visit,
             date=date_visit_now,
             status="ongoing",
             snapshot=None,
@@ -1792,21 +1797,38 @@
         swh_storage.origin_visit_status_add([visit_status1, visit_status2])
 
         origin_visit1 = swh_storage.origin_visit_get_latest(
-            origin_url, require_snapshot=True
+            origin1.url, require_snapshot=True
         )
         assert origin_visit1
         assert origin_visit1["status"] == "full"
         assert origin_visit1["snapshot"] == snapshot_id
 
         origin_visit2 = swh_storage.origin_visit_get_latest(
-            origin_url2, require_snapshot=False
+            origin2.url, require_snapshot=False
         )
-        assert origin_url2 != origin_url
+        assert origin2.url != origin1.url
         assert origin_visit2
         assert origin_visit2["status"] == "ongoing"
         assert origin_visit2["snapshot"] is None
         assert origin_visit2["metadata"] == {"intrinsic": "something"}
 
+        objects = list(swh_storage.journal_writer.journal.objects)
+        visit_status1_dict = ov1.to_dict()
+        visit_status1_dict.pop("type")
+        visit_status2_dict = ov2.to_dict()
+        visit_status2_dict.pop("type")
+
+        assert objects == [
+            ("origin", origin1),
+            ("origin", origin2),
+            ("origin_visit", ov1),
+            ("origin_visit_status", OriginVisitStatus.from_dict(visit_status1_dict)),
+            ("origin_visit", ov2),
+            ("origin_visit_status", OriginVisitStatus.from_dict(visit_status2_dict)),
+            ("origin_visit_status", visit_status1),
+            ("origin_visit_status", visit_status2),
+        ]
+
     def test_origin_visit_update(self, swh_storage):
         # given
         origin_url = swh_storage.origin_add_one(data.origin)