diff --git a/homeassistant/components/binary_sensor/bayesian.py b/homeassistant/components/binary_sensor/bayesian.py
index ac328fd1f41..13908fb5472 100644
--- a/homeassistant/components/binary_sensor/bayesian.py
+++ b/homeassistant/components/binary_sensor/bayesian.py
@@ -102,7 +102,13 @@ class BayesianBinarySensor(BinarySensorDevice):
 
         self.current_obs = OrderedDict({})
 
-        self.entity_obs = {obs['entity_id']: obs for obs in self._observations}
+        to_observe = set(obs['entity_id'] for obs in self._observations)
+
+        self.entity_obs = dict.fromkeys(to_observe, [])
+
+        for ind, obs in enumerate(self._observations):
+            obs["id"] = ind
+            self.entity_obs[obs['entity_id']].append(obs)
 
         self.watchers = {
             'numeric_state': self._process_numeric_state,
@@ -120,16 +126,17 @@ class BayesianBinarySensor(BinarySensorDevice):
             if new_state.state == STATE_UNKNOWN:
                 return
 
-            entity_obs = self.entity_obs[entity]
-            platform = entity_obs['platform']
+            entity_obs_list = self.entity_obs[entity]
 
-            self.watchers[platform](entity_obs)
+            for entity_obs in entity_obs_list:
+                platform = entity_obs['platform']
+
+                self.watchers[platform](entity_obs)
 
             prior = self.prior
             for obs in self.current_obs.values():
                 prior = update_probability(prior, obs['prob_true'],
                                            obs['prob_false'])
-
             self.probability = prior
 
             self.hass.async_add_job(self.async_update_ha_state, True)
@@ -140,20 +147,20 @@ class BayesianBinarySensor(BinarySensorDevice):
 
     def _update_current_obs(self, entity_observation, should_trigger):
         """Update current observation."""
-        entity = entity_observation['entity_id']
+        obs_id = entity_observation['id']
 
         if should_trigger:
             prob_true = entity_observation['prob_given_true']
             prob_false = entity_observation.get(
                 'prob_given_false', 1 - prob_true)
 
-            self.current_obs[entity] = {
+            self.current_obs[obs_id] = {
                 'prob_true': prob_true,
                 'prob_false': prob_false
             }
 
         else:
-            self.current_obs.pop(entity, None)
+            self.current_obs.pop(obs_id, None)
 
     def _process_numeric_state(self, entity_observation):
         """Add entity to current_obs if numeric state conditions are met."""
diff --git a/tests/components/binary_sensor/test_bayesian.py b/tests/components/binary_sensor/test_bayesian.py
index 61b110f247f..3b403c3702f 100644
--- a/tests/components/binary_sensor/test_bayesian.py
+++ b/tests/components/binary_sensor/test_bayesian.py
@@ -73,8 +73,7 @@ class TestBayesianBinarySensor(unittest.TestCase):
             'prob_false': 0.1,
             'prob_true': 0.9
         }], state.attributes.get('observations'))
-        self.assertAlmostEqual(0.77,
-                               state.attributes.get('probability'))
+        self.assertAlmostEqual(0.77, state.attributes.get('probability'))
 
         assert state.state == 'on'
 
@@ -155,6 +154,71 @@ class TestBayesianBinarySensor(unittest.TestCase):
 
         assert state.state == 'off'
 
+    def test_multiple_observations(self):
+        """Test sensor with multiple observations of same entity."""
+        config = {
+            'binary_sensor': {
+                'name':
+                'Test_Binary',
+                'platform':
+                'bayesian',
+                'observations': [{
+                    'platform': 'state',
+                    'entity_id': 'sensor.test_monitored',
+                    'to_state': 'blue',
+                    'prob_given_true': 0.8,
+                    'prob_given_false': 0.4
+                }, {
+                    'platform': 'state',
+                    'entity_id': 'sensor.test_monitored',
+                    'to_state': 'red',
+                    'prob_given_true': 0.2,
+                    'prob_given_false': 0.4
+                }],
+                'prior':
+                0.2,
+                'probability_threshold':
+                0.32,
+            }
+        }
+
+        assert setup_component(self.hass, 'binary_sensor', config)
+
+        self.hass.states.set('sensor.test_monitored', 'off')
+
+        state = self.hass.states.get('binary_sensor.test_binary')
+
+        self.assertEqual([], state.attributes.get('observations'))
+        self.assertEqual(0.2, state.attributes.get('probability'))
+
+        assert state.state == 'off'
+
+        self.hass.states.set('sensor.test_monitored', 'blue')
+        self.hass.block_till_done()
+        self.hass.states.set('sensor.test_monitored', 'off')
+        self.hass.block_till_done()
+        self.hass.states.set('sensor.test_monitored', 'blue')
+        self.hass.block_till_done()
+
+        state = self.hass.states.get('binary_sensor.test_binary')
+        self.assertEqual([{
+            'prob_true': 0.8,
+            'prob_false': 0.4
+        }], state.attributes.get('observations'))
+        self.assertAlmostEqual(0.33, state.attributes.get('probability'))
+
+        assert state.state == 'on'
+
+        self.hass.states.set('sensor.test_monitored', 'blue')
+        self.hass.block_till_done()
+        self.hass.states.set('sensor.test_monitored', 'red')
+        self.hass.block_till_done()
+
+        state = self.hass.states.get('binary_sensor.test_binary')
+        self.assertAlmostEqual(0.11, state.attributes.get('probability'))
+
+        assert state.state == 'off'
+
     def test_probability_updates(self):
         """Test probability update function."""
         prob_true = [0.3, 0.6, 0.8]