diff --git a/changelogs/fragments/4212-fixes-for-keycloak-user-federation.yml b/changelogs/fragments/4212-fixes-for-keycloak-user-federation.yml
new file mode 100644
index 0000000000..033add7a90
--- /dev/null
+++ b/changelogs/fragments/4212-fixes-for-keycloak-user-federation.yml
@@ -0,0 +1,8 @@
+---
+bugfixes:
+  - keycloak_user_federation - creating a user federation while specifying an
+    ID (that does not exist yet) no longer fail with a 404 Not Found
+    (https://github.com/ansible-collections/community.general/pull/4212).
+  - keycloak_user_federation - mappers auto-created by keycloak are matched and
+    merged by their name and no longer create duplicated entries
+    (https://github.com/ansible-collections/community.general/pull/4212).
diff --git a/plugins/modules/identity/keycloak/keycloak_user_federation.py b/plugins/modules/identity/keycloak/keycloak_user_federation.py
index f8e6d3aea4..4d623a4874 100644
--- a/plugins/modules/identity/keycloak/keycloak_user_federation.py
+++ b/plugins/modules/identity/keycloak/keycloak_user_federation.py
@@ -845,7 +845,7 @@ def main():
         before_comp = {}
 
     # if user federation exists, get associated mappers
-    if cid is not None:
+    if cid is not None and before_comp:
         before_comp['mappers'] = sorted(kc.get_components(urlencode(dict(parent=cid)), realm), key=lambda x: x.get('name'))
 
     # Build a proposed changeset from parameters given to this module
@@ -921,12 +921,23 @@ def main():
         after_comp = kc.create_component(desired_comp, realm)
 
         for mapper in updated_mappers:
-            if mapper.get('id') is not None:
-                kc.update_component(mapper, realm)
+            found = kc.get_components(urlencode(dict(parent=cid, name=mapper['name'])), realm)
+            if len(found) > 1:
+                module.fail_json(msg='Found multiple mappers with name `{name}`. Cannot continue.'.format(name=mapper['name']))
+            if len(found) == 1:
+                old_mapper = found[0]
             else:
-                if mapper.get('parentId') is None:
-                    mapper['parentId'] = after_comp['id']
-                mapper = kc.create_component(mapper, realm)
+                old_mapper = {}
+
+            new_mapper = old_mapper.copy()
+            new_mapper.update(mapper)
+
+            if new_mapper.get('id') is not None:
+                kc.update_component(new_mapper, realm)
+            else:
+                if new_mapper.get('parentId') is None:
+                    new_mapper['parentId'] = after_comp['id']
+                mapper = kc.create_component(new_mapper, realm)
 
         after_comp['mappers'] = updated_mappers
         result['end_state'] = sanitize(after_comp)
diff --git a/tests/unit/plugins/modules/identity/keycloak/test_keycloak_user_federation.py b/tests/unit/plugins/modules/identity/keycloak/test_keycloak_user_federation.py
index 674efeb237..a37ea1bb11 100644
--- a/tests/unit/plugins/modules/identity/keycloak/test_keycloak_user_federation.py
+++ b/tests/unit/plugins/modules/identity/keycloak/test_keycloak_user_federation.py
@@ -342,7 +342,7 @@ class TestKeycloakUserFederation(ModuleTestCase):
             ]
         }
         return_value_components_get = [
-            []
+            [], []
         ]
         return_value_component_create = [
             {
@@ -457,7 +457,7 @@ class TestKeycloakUserFederation(ModuleTestCase):
                 with self.assertRaises(AnsibleExitJson) as exec_info:
                     self.module.main()
 
-        self.assertEqual(len(mock_get_components.mock_calls), 1)
+        self.assertEqual(len(mock_get_components.mock_calls), 2)
         self.assertEqual(len(mock_get_component.mock_calls), 0)
         self.assertEqual(len(mock_create_component.mock_calls), 2)
         self.assertEqual(len(mock_update_component.mock_calls), 0)