diff --git a/indigo-matter.indigoPlugin/Contents/Info.plist b/indigo-matter.indigoPlugin/Contents/Info.plist
index f21c051..4f41ec8 100644
--- a/indigo-matter.indigoPlugin/Contents/Info.plist
+++ b/indigo-matter.indigoPlugin/Contents/Info.plist
@@ -20,7 +20,7 @@
 	<key>IwsApiVersion</key>
 	<string>1.0.0</string>
 	<key>PluginVersion</key>
-	<string>2026.4.1</string>
+	<string>2026.4.2</string>
 	<key>ServerApiVersion</key>
 	<string>3.6</string>
 </dict>
diff --git a/tests/test_device_zoo.py b/tests/test_device_zoo.py
index 6ef000f..1dedceb 100644
--- a/tests/test_device_zoo.py
+++ b/tests/test_device_zoo.py
@@ -13,7 +13,10 @@
   3. every spec's device_type_id exists in Devices.xml;
   4. every initial state is XML-declared or an Indigo built-in;
   5. every sensor-type spec carries explicit SupportsOnState /
-     SupportsSensorValue with exactly one True (the issue #56 class).
+     SupportsSensorValue with exactly one True (the issue #56 class);
+  6. no device type's <States> block redeclares a state key that a True
+     Supports* prop already derives natively (the PR #73 class — Indigo
+     rejects plugin-declared state keys that duplicate a native one).
 """
 from __future__ import annotations
 
@@ -54,6 +57,15 @@
     "matterThermostat", "matterWindowCovering", "matterLock", "matterValve",
 }
 
+# Supports* creation prop → the native Indigo state key it derives (PR #73:
+# Indigo rejects a plugin-declared <State> that duplicates one of these).
+NATIVE_STATE_KEY_BY_PROP = {
+    "SupportsSensorValue": "sensorValue",
+    "SupportsOnState": "onOffState",
+    "SupportsPowerMeter": "curEnergyLevel",
+    "SupportsEnergyMeter": "accumEnergyTotal",
+}
+
 
 
 def _raw(node_id, eps):
@@ -275,6 +287,20 @@ def test_zoo_sensor_specs_carry_explicit_display_props(name):
                 )
 
 
+@pytest.mark.parametrize("name", ZOO)
+def test_zoo_native_props_not_redeclared_in_devices_xml(name):
+    raw, _ = ZOO[name]
+    for specs in _specs_by_endpoint(raw).values():
+        for spec in specs:
+            declared = XML_STATES_BY_ID.get(spec.device_type_id, set())
+            for prop, key in NATIVE_STATE_KEY_BY_PROP.items():
+                if spec.props.get(prop) is True:
+                    assert key not in declared, (
+                        f"{name}: {spec.device_type_id} declares native state "
+                        f"'{key}' in Devices.xml even though {prop} is True"
+                    )
+
+
 def test_every_registered_handler_type_exists_in_devices_xml():
     # Registry-wide, zoo-independent: a handler pointing at a typo'd or
     # removed Devices.xml id would create devices that Indigo rejects.