diff --git a/homeassistant/bootstrap.py b/homeassistant/bootstrap.py
index a7476162265..2ba0681c2d6 100644
--- a/homeassistant/bootstrap.py
+++ b/homeassistant/bootstrap.py
@@ -22,6 +22,7 @@ from homeassistant.const import (
     CONF_CUSTOMIZE, CONF_LATITUDE, CONF_LONGITUDE, CONF_NAME,
     CONF_TEMPERATURE_UNIT, CONF_TIME_ZONE, EVENT_COMPONENT_LOADED,
     TEMP_CELCIUS, TEMP_FAHRENHEIT, PLATFORM_FORMAT, __version__)
+from homeassistant.exceptions import HomeAssistantError
 from homeassistant.helpers import (
     event_decorators, service, config_per_platform, extract_domain_configs)
 from homeassistant.helpers.entity import Entity
@@ -293,7 +294,10 @@ def from_config_file(config_path, hass=None, verbose=False, daemon=False,
 
     enable_logging(hass, verbose, daemon, log_rotate_days)
 
-    config_dict = config_util.load_yaml_config_file(config_path)
+    try:
+        config_dict = config_util.load_yaml_config_file(config_path)
+    except HomeAssistantError:
+        return None
 
     return from_config_dict(config_dict, hass, enable_log=False,
                             skip_pip=skip_pip)
diff --git a/homeassistant/components/device_tracker/__init__.py b/homeassistant/components/device_tracker/__init__.py
index 240ac532e5c..1866e972e28 100644
--- a/homeassistant/components/device_tracker/__init__.py
+++ b/homeassistant/components/device_tracker/__init__.py
@@ -204,6 +204,7 @@ class DeviceTracker(object):
                 return
 
             # If no device can be found, create it
+            dev_id = util.ensure_unique_string(dev_id, self.devices.keys())
             device = Device(
                 self.hass, self.consider_home, self.home_range, self.track_new,
                 dev_id, mac, (host_name or dev_id).replace('_', ' '))
diff --git a/homeassistant/const.py b/homeassistant/const.py
index 9bb3d3fba7a..349a820dfc1 100644
--- a/homeassistant/const.py
+++ b/homeassistant/const.py
@@ -1,7 +1,7 @@
 # coding: utf-8
 """Constants used by Home Assistant components."""
 
-__version__ = "0.17.1"
+__version__ = "0.17.2"
 REQUIRED_PYTHON_VER = (3, 4)
 
 PLATFORM_FORMAT = '{}.{}'
diff --git a/homeassistant/util/yaml.py b/homeassistant/util/yaml.py
index b60d81fae55..1c9ff8c1c16 100644
--- a/homeassistant/util/yaml.py
+++ b/homeassistant/util/yaml.py
@@ -29,10 +29,9 @@ def load_yaml(fname):
             # If configuration file is empty YAML returns None
             # We convert that to an empty dict
             return yaml.load(conf_file, Loader=SafeLineLoader) or {}
-    except yaml.YAMLError:
-        error = 'Error reading YAML configuration file {}'.format(fname)
-        _LOGGER.exception(error)
-        raise HomeAssistantError(error)
+    except yaml.YAMLError as exc:
+        _LOGGER.error(exc)
+        raise HomeAssistantError(exc)
 
 
 def _include_yaml(loader, node):
@@ -55,9 +54,12 @@ def _ordered_dict(loader, node):
         line = getattr(node, '__line__', 'unknown')
         if key in seen:
             fname = getattr(loader.stream, 'name', '')
-            raise yaml.YAMLError("ERROR: duplicate key: \"{}\""
-                                 " in {} line {} and {}"
-                                 .format(key, fname, seen[key], line))
+            first_mark = yaml.Mark(fname, 0, seen[key], -1, None, None)
+            second_mark = yaml.Mark(fname, 0, line, -1, None, None)
+            raise yaml.MarkedYAMLError(
+                context="duplicate key: \"{}\"".format(key),
+                context_mark=first_mark, problem_mark=second_mark,
+            )
         seen[key] = line
 
     return OrderedDict(nodes)
diff --git a/tests/components/device_tracker/test_init.py b/tests/components/device_tracker/test_init.py
index 8cd3df96198..fb6b5240f95 100644
--- a/tests/components/device_tracker/test_init.py
+++ b/tests/components/device_tracker/test_init.py
@@ -197,3 +197,16 @@ class TestComponentsDeviceTracker(unittest.TestCase):
         mock_see.assert_called_once_with(
             mac=mac, dev_id=dev_id, host_name=host_name,
             location_name=location_name, gps=gps)
+
+    def test_not_write_duplicate_yaml_keys(self):
+        """Test that the device tracker will not generate invalid YAML."""
+        self.assertTrue(device_tracker.setup(self.hass, {}))
+
+        device_tracker.see(self.hass, 'mac_1', host_name='hello')
+        device_tracker.see(self.hass, 'mac_2', host_name='hello')
+
+        self.hass.pool.block_till_done()
+
+        config = device_tracker.load_config(self.yaml_devices, self.hass,
+                                            timedelta(seconds=0), 0)
+        assert len(config) == 2