diff --git a/homeassistant/helpers/dispatcher.py b/homeassistant/helpers/dispatcher.py
index d1f7b2b97f9..12a6616b009 100644
--- a/homeassistant/helpers/dispatcher.py
+++ b/homeassistant/helpers/dispatcher.py
@@ -41,26 +41,13 @@ def async_dispatcher_connect(
     """
     if DATA_DISPATCHER not in hass.data:
         hass.data[DATA_DISPATCHER] = {}
-
-    job = HassJob(
-        catch_log_exception(
-            target,
-            lambda *args: "Exception in {} when dispatching '{}': {}".format(
-                # Functions wrapped in partial do not have a __name__
-                getattr(target, "__name__", None) or str(target),
-                signal,
-                args,
-            ),
-        )
-    )
-
-    hass.data[DATA_DISPATCHER].setdefault(signal, []).append(job)
+    hass.data[DATA_DISPATCHER].setdefault(signal, {})[target] = None
 
     @callback
     def async_remove_dispatcher() -> None:
         """Remove signal listener."""
         try:
-            hass.data[DATA_DISPATCHER][signal].remove(job)
+            del hass.data[DATA_DISPATCHER][signal][target]
         except (KeyError, ValueError):
             # KeyError is key target listener did not exist
             # ValueError if listener did not exist within signal
@@ -75,6 +62,21 @@ def dispatcher_send(hass: HomeAssistant, signal: str, *args: Any) -> None:
     hass.loop.call_soon_threadsafe(async_dispatcher_send, hass, signal, *args)
 
 
+def _generate_job(signal: str, target: Callable[..., Any]) -> HassJob:
+    """Generate a HassJob for a signal and target."""
+    return HassJob(
+        catch_log_exception(
+            target,
+            lambda *args: "Exception in {} when dispatching '{}': {}".format(
+                # Functions wrapped in partial do not have a __name__
+                getattr(target, "__name__", None) or str(target),
+                signal,
+                args,
+            ),
+        )
+    )
+
+
 @callback
 @bind_hass
 def async_dispatcher_send(hass: HomeAssistant, signal: str, *args: Any) -> None:
@@ -82,7 +84,9 @@ def async_dispatcher_send(hass: HomeAssistant, signal: str, *args: Any) -> None:
 
     This method must be run in the event loop.
     """
-    target_list = hass.data.get(DATA_DISPATCHER, {}).get(signal, [])
-
-    for job in target_list:
+    target_list = hass.data.get(DATA_DISPATCHER, {}).get(signal, {})
+    for target, job in target_list.items():
+        if job is None:
+            job = _generate_job(signal, target)
+            target_list[target] = job
         hass.async_add_hass_job(job, *args)
diff --git a/tests/components/cast/test_media_player.py b/tests/components/cast/test_media_player.py
index 00626cc8c16..61a6067578a 100644
--- a/tests/components/cast/test_media_player.py
+++ b/tests/components/cast/test_media_player.py
@@ -311,7 +311,7 @@ async def test_internal_discovery_callback_fill_out_group_fail(
         await hass.async_block_till_done()
 
         # when called with incomplete info, it should use HTTP to get missing
-        discover = signal.mock_calls[0][1][0]
+        discover = signal.mock_calls[-1][1][0]
         assert discover == full_info
         get_multizone_status_mock.assert_called_once()
 
@@ -352,7 +352,7 @@ async def test_internal_discovery_callback_fill_out_group(
         await hass.async_block_till_done()
 
         # when called with incomplete info, it should use HTTP to get missing
-        discover = signal.mock_calls[0][1][0]
+        discover = signal.mock_calls[-1][1][0]
         assert discover == full_info
         get_multizone_status_mock.assert_called_once()
 
@@ -423,23 +423,25 @@ async def test_internal_discovery_callback_fill_out_cast_type_manufacturer(
         # when called with incomplete info, it should use HTTP to get missing
         get_cast_type_mock.assert_called_once()
         assert get_cast_type_mock.call_count == 1
-        discover = signal.mock_calls[0][1][0]
+        discover = signal.mock_calls[2][1][0]
         assert discover == full_info
         assert "Fetched cast details for unknown model 'Chromecast'" in caplog.text
 
+        signal.reset_mock()
         # Call again, the model name should be fetched from cache
         discover_cast(FAKE_MDNS_SERVICE, info)
         await hass.async_block_till_done()
         assert get_cast_type_mock.call_count == 1  # No additional calls
-        discover = signal.mock_calls[1][1][0]
+        discover = signal.mock_calls[0][1][0]
         assert discover == full_info
 
+        signal.reset_mock()
         # Call for another model, need to call HTTP again
         get_cast_type_mock.return_value = full_info2.cast_info
         discover_cast(FAKE_MDNS_SERVICE, info2)
         await hass.async_block_till_done()
         assert get_cast_type_mock.call_count == 2
-        discover = signal.mock_calls[2][1][0]
+        discover = signal.mock_calls[0][1][0]
         assert discover == full_info2