diff --git a/beets/library.py b/beets/library.py
index 2430f71258..58f780fcd3 100644
--- a/beets/library.py
+++ b/beets/library.py
@@ -360,8 +360,9 @@ def remove(self):
         plugins.send("database_change", lib=self._db, model=self)
 
     def add(self, lib=None):
+        # super().add() calls self.store(), which sends `database_change`,
+        # so don't do it here
         super().add(lib)
-        plugins.send("database_change", lib=self._db, model=self)
 
     def __format__(self, spec):
         if not spec:
diff --git a/beets/plugins.py b/beets/plugins.py
index 299c418157..e9ec64cba9 100644
--- a/beets/plugins.py
+++ b/beets/plugins.py
@@ -25,6 +25,7 @@
 
 import beets
 from beets import logging
+from beets.types import EventType
 
 PLUGIN_NAMESPACE = "beetsplug"
 
@@ -204,7 +205,7 @@ def add_media_field(self, name, descriptor):
     _raw_listeners = None
     listeners = None
 
-    def register_listener(self, event, func):
+    def register_listener(self, event: EventType, func):
         """Add a function as a listener for the specified event."""
         wrapped_func = self._set_log_level_and_params(logging.WARNING, func)
 
diff --git a/beets/types.py b/beets/types.py
new file mode 100644
index 0000000000..d5fc01eec9
--- /dev/null
+++ b/beets/types.py
@@ -0,0 +1,33 @@
+from typing import Literal
+
+EventType = Literal[
+    "pluginload",
+    "import",
+    "album_imported",
+    "album_removed",
+    "item_copied",
+    "item_imported",
+    "before_item_moved",
+    "item_moved",
+    "item_linked",
+    "item_hardlinked",
+    "item_reflinked",
+    "item_removed",
+    "write",
+    "after_write",
+    "import_task_created",
+    "import_task_start",
+    "import_task_apply",
+    "import_task_before_choice",
+    "import_task_choice",
+    "import_task_files",
+    "library_opened",
+    "database_change",
+    "cli_exit",
+    "import_begin",
+    "trackinfo_received",
+    "albuminfo_received",
+    "before_choose_candidate",
+    "mb_track_extract",
+    "mb_album_extract",
+]
diff --git a/beets/util/hidden.py b/beets/util/hidden.py
index d2c66fac0f..e296e8c999 100644
--- a/beets/util/hidden.py
+++ b/beets/util/hidden.py
@@ -23,13 +23,15 @@
 from typing import Union
 
 
-def is_hidden(path: Union[bytes, Path]) -> bool:
+def is_hidden(path: Union[bytes, str, Path]) -> bool:
     """
     Determine whether the given path is treated as a 'hidden file' by the OS.
     """
 
     if isinstance(path, bytes):
         path = Path(os.fsdecode(path))
+    elif isinstance(path, str):
+        path = Path(path)
 
     # TODO: Avoid doing a platform check on every invocation of the function.
     # TODO: Stop supporting 'bytes' inputs once 'pathlib' is fully integrated.
diff --git a/docs/changelog.rst b/docs/changelog.rst
index 9fb3b9e3ff..69fc7bc100 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -27,6 +27,9 @@ Bug fixes:
   :bug:`5265`
   :bug:`5371`
   :bug:`4715`
+* Fix an issue where calling `Library.add` would cause the `database_change`
+  event to be sent twice, not once.
+  :bug:`5560`
 
 For packagers:
 
diff --git a/test/test_database_change.py b/test/test_database_change.py
new file mode 100644
index 0000000000..a67a095b71
--- /dev/null
+++ b/test/test_database_change.py
@@ -0,0 +1,26 @@
+import os
+
+import beets
+import beets.logging as blog
+from beets.test import _common
+from beets.test.helper import BeetsTestCase, capture_log
+
+
+class DatabaseChangeTestBase(BeetsTestCase):
+    def test_item_added_one_database_change(self):
+        self.item = _common.item()
+        self.item.path = beets.util.normpath(
+            os.path.join(
+                self.temp_dir,
+                b"a",
+                b"b.mp3",
+            )
+        )
+        self.item.album = "a"
+        self.item.title = "b"
+
+        blog.getLogger("beets").set_global_level(blog.DEBUG)
+        with capture_log() as logs:
+            self.lib.add(self.item)
+
+        assert logs.count("Sending event: database_change") == 1