diff --git a/src/ert/config/summary_config.py b/src/ert/config/summary_config.py
index 846ad4dbf78..486657fe2a3 100644
--- a/src/ert/config/summary_config.py
+++ b/src/ert/config/summary_config.py
@@ -94,10 +94,11 @@ def read_from_file(self, run_path: str, iens: int) -> xr.Dataset:
             )
             data.append(np_vector)
 
-        return xr.Dataset(
+        ds = xr.Dataset(
             {"values": (["name", "time"], data)},
             coords={"time": axis, "name": keys},
         )
+        return ds.drop_duplicates(["time", "name"])
 
     def _should_load_summary_key(self, data_key: Any, user_set_keys: set[str]) -> bool:
         return any(fnmatch(data_key, key) for key in user_set_keys)
diff --git a/tests/unit_tests/scenarios/test_summary_response.py b/tests/unit_tests/scenarios/test_summary_response.py
index e542455e287..2e296b948dd 100644
--- a/tests/unit_tests/scenarios/test_summary_response.py
+++ b/tests/unit_tests/scenarios/test_summary_response.py
@@ -153,3 +153,24 @@ def run_sim(dates, value, fname="ECLIPSE_CASE"):
         )
         t_step["FOPR"] = value
     ecl_sum.fwrite()
+
+
+def test_that_duplicate_summary_time_steps_does_not_fail(
+    setup_configuration,
+    prior_ensemble,
+    target_ensemble,
+):
+    ert = setup_configuration
+    ert.sample_prior(prior_ensemble, list(range(ert.getEnsembleSize())))
+    response_times = [
+        [datetime(2014, 9, 9)],
+        [datetime(2014, 9, 9)],
+        [datetime(2014, 9, 9), datetime(2014, 9, 9)],
+        [datetime(2014, 9, 9)],
+        [datetime(2014, 9, 9), datetime(1988, 9, 9)],
+    ]
+    create_responses(ert, prior_ensemble, response_times)
+
+    es_update = ESUpdate(ert)
+
+    es_update.smootherUpdate(prior_ensemble, target_ensemble, "an id")