Fixed #35090 -- Deprecated registering URL converters with the same name.

docs/internals/deprecation.txt

@@ -74,6 +74,9 @@ details on these changes.
 * The setter for ``django.contrib.gis.gdal.OGRGeometry.coord_dim`` will be
   removed.
 
+* ``django.urls.register_converter()`` will no longer allow overriding existing
+  converters.
+
 .. _deprecation-removed-in-5.1:
 
 5.1

docs/ref/urls.txt

@@ -120,6 +120,10 @@ The ``converter`` argument is a converter class, and ``type_name`` is the
 converter name to use in path patterns. See
 :ref:`registering-custom-path-converters` for an example.
 
+.. deprecated:: 5.1
+
+    Overriding existing converters is deprecated.
+
 ==================================================
 ``django.conf.urls`` functions for use in URLconfs
 ==================================================

docs/releases/5.1.txt

@@ -419,6 +419,9 @@ Miscellaneous
 * Setting ``django.contrib.gis.gdal.OGRGeometry.coord_dim`` is deprecated. Use
   :meth:`~django.contrib.gis.gdal.OGRGeometry.set_3d` instead.
 
+* Overriding existing converters with ``django.urls.register_converter()`` is
+  deprecated.
+
 Features removed in 5.1
 =======================
 

docs/topics/http/urls.txt

@@ -183,6 +183,11 @@ Register custom converter classes in your URLconf using
         ...,
     ]
 
+.. deprecated:: 5.1
+
+    Overriding existing converters with ``django.urls.register_converter()`` is
+    deprecated.
+
 Using regular expressions
 =========================