Ensure allow_duplicates: true enables to run single role multiple times (#64902) (#65063)

* Ensure `allow_duplicates: true` enables to run single role multiple times(#64902)

* Changed return value in `_load_roles` . Fixes #64902

* Add changelog fragment

* Add an integration test for the issue

* Fix changelog generation error and integration test.

* Fix yaml syntax error in changelog fragment

test/integration/targets/include_import/roles/dup_allowed_role/meta/main.yml

@@ -0,0 +1,2 @@
+---
+allow_duplicates: true

test/integration/targets/include_import/roles/dup_allowed_role/tasks/main.yml

@@ -0,0 +1,3 @@
+---
+- debug:
+    msg: "Tasks file inside role"

test/integration/targets/include_import/runme.sh

@@ -104,3 +104,7 @@ ansible-playbook test_loop_var_bleed.yaml "$@"
 
 # https://github.com/ansible/ansible/issues/56580
 ansible-playbook valid_include_keywords/playbook.yml "$@"
+
+# https://github.com/ansible/ansible/issues/64902
+ansible-playbook tasks/test_allow_single_role_dup.yml 2>&1 | tee test_allow_single_role_dup.out
+test "$(grep -c 'ok=3' test_allow_single_role_dup.out)" = 1

test/integration/targets/include_import/tasks/test_allow_single_role_dup.yml

@@ -0,0 +1,8 @@
+---
+- name: test for allow_duplicates with single role
+  hosts: localhost
+  gather_facts: false
+  roles:
+    - dup_allowed_role
+    - dup_allowed_role
+    - dup_allowed_role