diff --git a/swh/lister/cran/lister.py b/swh/lister/cran/lister.py
--- a/swh/lister/cran/lister.py
+++ b/swh/lister/cran/lister.py
@@ -45,9 +45,18 @@
 
     def get_origins_from_page(self, page: PageType) -> Iterator[ListedOrigin]:
         assert self.lister_obj.id is not None
+
+        seen_urls = set()
         for package_info in page:
             origin_url, artifact_url = compute_origin_urls(package_info)
 
+            if origin_url in seen_urls:
+                # prevent multiple listing of an origin,
+                # most recent version will be listed first
+                continue
+
+            seen_urls.add(origin_url)
+
             yield ListedOrigin(
                 lister_id=self.lister_obj.id,
                 url=origin_url,
@@ -108,22 +117,28 @@
     packaged_at_str = package_info.get("Packaged", "")
     packaged_at = None
     if packaged_at_str:
-        try:
-            # Packaged field format: "%Y-%m-%d %H:%M:%S UTC; <packager>",
-            packaged_at = datetime.strptime(
-                packaged_at_str.split(" UTC;")[0], "%Y-%m-%d %H:%M:%S",
-            ).replace(tzinfo=timezone.utc)
-        except Exception:
+        packaged_at_str = packaged_at_str.replace(" UTC", "")
+        # Packaged field possible formats:
+        #   - "%Y-%m-%d %H:%M:%S[.%f] UTC; <packager>",
+        #   - "%a %b %d %H:%M:%S %Y; <packager>"
+        for date_format in (
+            "%Y-%m-%d %H:%M:%S",
+            "%Y-%m-%d %H:%M:%S.%f",
+            "%a %b %d %H:%M:%S %Y",
+        ):
             try:
-                # Some old packages have a different date format:
-                # "%a %b %d %H:%M:%S %Y; <packager>"
                 packaged_at = datetime.strptime(
-                    packaged_at_str.split(";")[0], "%a %b %d %H:%M:%S %Y",
+                    packaged_at_str.split(";")[0], date_format,
                 ).replace(tzinfo=timezone.utc)
+                break
             except Exception:
-                logger.debug(
-                    "Could not parse %s package release date: %s",
-                    package_info["Package"],
-                    packaged_at_str,
-                )
+                continue
+
+        if packaged_at is None:
+            logger.debug(
+                "Could not parse %s package release date: %s",
+                package_info["Package"],
+                packaged_at_str,
+            )
+
     return packaged_at
diff --git a/swh/lister/cran/tests/test_lister.py b/swh/lister/cran/tests/test_lister.py
--- a/swh/lister/cran/tests/test_lister.py
+++ b/swh/lister/cran/tests/test_lister.py
@@ -40,6 +40,20 @@
     assert parse_packaged_date(common_date_format) == datetime(
         year=2017, month=4, day=26, hour=11, minute=36, second=15, tzinfo=timezone.utc
     )
+    common_date_format = {
+        "Package": "test",
+        "Packaged": "2017-04-26 11:36:15.123456 UTC; Jonathan",
+    }
+    assert parse_packaged_date(common_date_format) == datetime(
+        year=2017,
+        month=4,
+        day=26,
+        hour=11,
+        minute=36,
+        second=15,
+        microsecond=123456,
+        tzinfo=timezone.utc,
+    )
     old_date_format = {
         "Package": "test",
         "Packaged": "Thu Mar 30 10:48:35 2006; hornik",
@@ -91,6 +105,22 @@
         filtered_origins[0].last_update == parse_packaged_date(package_info)
 
 
+def test_cran_lister_duplicated_origins(datadir, swh_scheduler, mocker):
+    with open(path.join(datadir, "list-r-packages.json")) as f:
+        cran_data = json.loads(f.read())
+
+    lister = CRANLister(swh_scheduler)
+
+    mock_cran = mocker.patch("swh.lister.cran.lister.read_cran_data")
+
+    mock_cran.return_value = cran_data + cran_data
+
+    stats = lister.run()
+
+    assert stats.pages == 1
+    assert stats.origins == len(cran_data)
+
+
 @pytest.mark.parametrize(
     "credentials, expected_credentials",
     [