fix(help panel): prevent duplicated key displays (#5066)

* fix(help panel): prevent duplicated key displays

* fix changelog update

* de-dupe key displaus with keymaps

* rename variables for clarity

* change to dict.fromkeys for faster de-duping

Author: TomJGooding

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
+## Unreleased
+
+### Fixed
+
+- Fixed duplicated key displays in the help panel https://github.com/Textualize/textual/issues/5037
+
 ## [0.85.2] - 2024-11-02
 
 - Fixed broken focus-within https://github.com/Textualize/textual/pull/5190

src/textual/widgets/_key_panel.py

@@ -90,11 +90,13 @@ def render_description(binding: Binding) -> Text:
             get_key_display = self.app.get_key_display
             for multi_bindings in action_to_bindings.values():
                 binding, enabled, tooltip = multi_bindings[0]
-                key_display = " ".join(
-                    get_key_display(binding) for binding, _, _ in multi_bindings
+                keys_display = " ".join(
+                    dict.fromkeys(  # Remove duplicates while preserving order
+                        get_key_display(binding) for binding, _, _ in multi_bindings
+                    )
                 )
                 table.add_row(
-                    Text(key_display, style=key_style),
+                    Text(keys_display, style=key_style),
                     render_description(binding),
                 )
             if namespace != previous_namespace: