diff --git a/module_build_service/scheduler/submit.py b/module_build_service/scheduler/submit.py
index c4a3d44f..06c7ee00 100644
--- a/module_build_service/scheduler/submit.py
+++ b/module_build_service/scheduler/submit.py
@@ -104,7 +104,8 @@ def record_module_build_arches(mmd, build):
         arch_obj = db_session.query(models.ModuleArch).filter_by(name=arch).first()
         if not arch_obj:
             arch_obj = models.ModuleArch(name=arch)
-        build.arches.append(arch_obj)
+        if arch_obj not in build.arches:
+            build.arches.append(arch_obj)
 
     db_session.commit()
 
diff --git a/tests/test_scheduler/test_submit.py b/tests/test_scheduler/test_submit.py
index cbdb032d..5127d6bc 100644
--- a/tests/test_scheduler/test_submit.py
+++ b/tests/test_scheduler/test_submit.py
@@ -87,6 +87,10 @@ class TestSubmit:
         arches = {arch.name for arch in build.arches}
         assert arches == set(get_build_arches.return_value)
 
+        # Ensure the function is idempotent
+        record_module_build_arches(build.mmd(), build)
+        assert len(build.arches) == len(get_build_arches.return_value)
+
     @pytest.mark.parametrize(
         "scmurl",
         [