diff --git a/tests/test_integration_shape_classify.py b/tests/test_integration_shape_classify.py
index c4f0f32..8b74470 100644
--- a/tests/test_integration_shape_classify.py
+++ b/tests/test_integration_shape_classify.py
@@ -531,7 +531,11 @@ async def test_derive_groups_land_on_rows_and_in_the_summary(seeded):
 
     summary = proposal_summary(await live_rows(pid))
     assert summary["proposed"] == 1
-    assert [g["group"] for g in summary["derive_groups"]][0] == "name:css:card"
+    # #2872: the body-identical group (a real copy) outranks the bigger name
+    # group (usually convention), even at size 2 vs 3.
+    order = [g["group"] for g in summary["derive_groups"]]
+    assert order[0].startswith("dup:") and order[1] == "name:css:card"
+    assert summary["derive_groups"][0]["files"] == 2
     assert summary["derive_groups"][0]["label"] == ".card"
     assert summary["derive_groups"][0]["size"] == 3