diff --git a/e2e/scenario_inputs/pi_web_api_scouter_distinct_tag_timestamps.json b/e2e/scenario_inputs/pi_web_api_scouter_distinct_tag_timestamps_multi_point.json
similarity index 91%
rename from e2e/scenario_inputs/pi_web_api_scouter_distinct_tag_timestamps.json
rename to e2e/scenario_inputs/pi_web_api_scouter_distinct_tag_timestamps_multi_point.json
index a5be268..e4c24de 100644
--- a/e2e/scenario_inputs/pi_web_api_scouter_distinct_tag_timestamps.json
+++ b/e2e/scenario_inputs/pi_web_api_scouter_distinct_tag_timestamps_multi_point.json
@@ -1,8 +1,8 @@
 {
   "workflow_input": {
     "model_id": "13",
-    "model_name": "PI Distinct Tag Timestamps",
-    "schedule_name": "pi-distinct-ts",
+    "model_name": "PI Distinct Tag Timestamps (max_count>1)",
+    "schedule_name": "pi-distinct-ts-n",
     "trigger_laborious": false,
     "filters": {},
     "schema": "sientia_data",
diff --git a/e2e/scenario_inputs/pi_web_api_scouter_distinct_tag_timestamps_single_point.json b/e2e/scenario_inputs/pi_web_api_scouter_distinct_tag_timestamps_single_point.json
new file mode 100644
index 0000000..f400051
--- /dev/null
+++ b/e2e/scenario_inputs/pi_web_api_scouter_distinct_tag_timestamps_single_point.json
@@ -0,0 +1,34 @@
+{
+  "workflow_input": {
+    "model_id": "14",
+    "model_name": "PI Distinct Tag Timestamps (max_count=1)",
+    "schedule_name": "pi-distinct-ts-1",
+    "trigger_laborious": false,
+    "filters": {},
+    "schema": "sientia_data",
+    "table_name": "laborious_data",
+    "retention_time": 3600,
+    "fill_missing_tags": false,
+    "model_tags": {
+      "tag_early": {"webid": "w1", "aggr_func": "lts", "data_range": [0, 1000], "frequency": 60000},
+      "tag_late": {"webid": "w2", "aggr_func": "lts", "data_range": [0, 1000], "frequency": 60000}
+    },
+    "pi_web_api_query": {
+      "endpoint": "/streamsets/recorded",
+      "period": "*-1d",
+      "max_count": 1,
+      "api_timeout": 30
+    }
+  },
+  "pi_web_api_server": {
+    "mode": "success",
+    "rows": [
+      {"name": "tag_early", "timestamp": "2024-06-01T12:00:00Z", "value": 10},
+      {"name": "tag_late", "timestamp": "2024-06-01T15:00:00Z", "value": 100}
+    ]
+  },
+  "expected_rows": {
+    "tag_early": {"value": 10.0, "timestamp": "2024-06-01T12:00:00Z"},
+    "tag_late": {"value": 100.0, "timestamp": "2024-06-01T15:00:00Z"}
+  }
+}
diff --git a/e2e/scenarios.md b/e2e/scenarios.md
index deab58e..3c9f87e 100644
--- a/e2e/scenarios.md
+++ b/e2e/scenarios.md
@@ -63,10 +63,11 @@ Five tags with `avg` / `mdn` / `max` / `min` / `lts`; assert five distinct `vari
 
 ### 2.1.4 Distinct tag timestamps preserved
 
-Regression test for SIENTIAPDE-1993. Two tags with `max_count=2`, each with two historical
-points, but at very different times (`tag_early` around 12:00, `tag_late` around 15:00); assert
-each tag's stored `timestamp` in Postgres equals its own last real point, not the batch-wide
-max across tags.
+Regression test for SIENTIAPDE-1993, parametrized over `max_count=1` and `max_count>1`. Two
+tags (`tag_early` around 12:00, `tag_late` around 15:00) per case; assert each tag's stored
+`timestamp` in Postgres equals its own latest point after aggregation, not the other tag's
+(the batch-wide max across tags) — the invariant must hold whether a tag has one point or
+several historical points.
 
 ### 2.2.1 Empty response early exit
 
diff --git a/e2e/test_pi_web_api_scouter_main_workflow.py b/e2e/test_pi_web_api_scouter_main_workflow.py
index 6c9bfbb..3f7c447 100644
--- a/e2e/test_pi_web_api_scouter_main_workflow.py
+++ b/e2e/test_pi_web_api_scouter_main_workflow.py
@@ -106,19 +106,29 @@ async def test_scenario_2_1_3_debug_data_package(
 
 @pytest.mark.e2e
 @pytest.mark.asyncio
+@pytest.mark.parametrize(
+    'scenario_name, workflow_id_prefix',
+    [
+        ('pi_web_api_scouter_distinct_tag_timestamps_single_point', 'pi-distinct-ts-1'),
+        ('pi_web_api_scouter_distinct_tag_timestamps_multi_point', 'pi-distinct-ts-n'),
+    ],
+    ids=['max_count_1', 'max_count_gt_1'],
+)
 async def test_scenario_2_1_4_distinct_tag_timestamps_preserved(
     temporal_env: WorkflowEnvironment,
     temporal_worker: Worker,
     pi_web_api_server: PIWebAPITestServer,
     postgres_engine,
+    scenario_name: str,
+    workflow_id_prefix: str,
 ):
     """
-    Regression test for SIENTIAPDE-1993: with max_count > 1 and tags whose real
-    latest points fall at different times, each tag's stored row must keep its
-    own real timestamp instead of collapsing to the batch-wide maximum across
-    all tags.
+    Regression test for SIENTIAPDE-1993: whether a tag has a single point
+    (max_count=1) or several historical points (max_count>1), each tag's
+    stored row must keep the timestamp of its own latest point after
+    aggregation, not another tag's timestamp from the same batch.
     """
-    scenario = load_scenario_input('pi_web_api_scouter_distinct_tag_timestamps')
+    scenario = load_scenario_input(scenario_name)
     apply_pi_web_api_server_config(pi_web_api_server, scenario.get('pi_web_api_server'))
     workflow_input = scenario['workflow_input']
 
@@ -126,7 +136,7 @@ async def test_scenario_2_1_4_distinct_tag_timestamps_preserved(
         temporal_env.client,
         PIWebAPIScouter.run,
         workflow_input,
-        make_workflow_id('pi-distinct-ts'),
+        make_workflow_id(workflow_id_prefix),
     )
 
     rows = {