Update djangocms_frontend/cms_plugins.py

Co-authored-by: sourcery-ai[bot] <58596630+sourcery-ai[bot]@users.noreply.github.com>

Author: fsbraun

djangocms_frontend/cms_plugins.py

@@ -22,9 +22,17 @@ def update_plugin_pool():
             # Loop through the slot plugins associated with the current plugin
             for slot_plugin in slot_plugins:
                 # Add the slot plugin to the global namespace
-                globals()[slot_plugin.__name__] = slot_plugin
-                # Register the slot plugin with the plugin pool
-                plugin_pool.register_plugin(slot_plugin)
+            # Register slot plugins, checking for name conflicts
+            for slot_plugin in slot_plugins:
+                if slot_plugin.__name__ not in plugin_pool.plugins:
+                    globals()[slot_plugin.__name__] = slot_plugin
+                    plugin_pool.register_plugin(slot_plugin)
+                else:
+                    raise ImproperlyConfigured(
+                        f"Cannot register slot plugin {slot_plugin.__name__} "
+                        f"since a plugin {slot_plugin.__name__} is already registered "
+                        f"by {plugin_pool.plugins[slot_plugin.__name__].__module__}."
+                    )
         else:
             raise ImproperlyConfigured(
                 f"Cannot register frontend component {key} since a plugin {plugin.__name__} "