diff --git a/llama-index-core/llama_index/core/graph_stores/types.py b/llama-index-core/llama_index/core/graph_stores/types.py
index a96ddbbe827..752f080d143 100644
--- a/llama-index-core/llama_index/core/graph_stores/types.py
+++ b/llama-index-core/llama_index/core/graph_stores/types.py
@@ -161,9 +161,6 @@ def get_triplets(self) -> List[Triplet]:
     def add_triplet(self, triplet: Triplet) -> None:
         """Add a triplet."""
         subj, rel, obj = triplet
-        if (subj.id, rel.id, obj.id) in self.triplets:
-            return
-
         self.triplets.add((subj.id, rel.id, obj.id))
         self.nodes[subj.id] = subj
         self.nodes[obj.id] = obj
diff --git a/llama-index-core/tests/graph_stores/test_simple_lpg_upserts.py b/llama-index-core/tests/graph_stores/test_simple_lpg_upserts.py
new file mode 100644
index 00000000000..c1cf03c17ba
--- /dev/null
+++ b/llama-index-core/tests/graph_stores/test_simple_lpg_upserts.py
@@ -0,0 +1,45 @@
+import pytest
+
+from llama_index.core.graph_stores.simple_labelled import SimplePropertyGraphStore
+from llama_index.core.graph_stores.types import EntityNode, Relation
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize("use_async", [False, True])
+async def test_relation_upsert_updates_existing_properties(use_async: bool) -> None:
+    store = SimplePropertyGraphStore()
+    alice = EntityNode(name="Alice", properties={"role": "author"})
+    bob = EntityNode(name="Bob", properties={"role": "reviewer"})
+    original = Relation(
+        label="KNOWS",
+        source_id=alice.id,
+        target_id=bob.id,
+        properties={"confidence": 0.1},
+    )
+    other = Relation(label="MENTIONS", source_id=alice.id, target_id=bob.id)
+    updated = Relation(
+        label="KNOWS",
+        source_id=alice.id,
+        target_id=bob.id,
+        properties={"confidence": 0.9},
+    )
+    store.upsert_nodes([alice, bob])
+    store.upsert_relations([original, other])
+
+    if use_async:
+        await store.aupsert_relations([updated])
+    else:
+        store.upsert_relations([updated])
+
+    assert store.get_triplets(relation_names=["KNOWS"]) == [(alice, updated, bob)]
+    assert store.get_triplets(relation_names=["MENTIONS"]) == [(alice, other, bob)]
+    assert len(store.graph.triplets) == 2
+    assert len(store.graph.relations) == 2
+    assert store.get(ids=[alice.id, bob.id]) == [alice, bob]
+
+    if use_async:
+        await store.aupsert_relations([updated])
+    else:
+        store.upsert_relations([updated])
+    assert len(store.graph.triplets) == 2
+    assert store.get_triplets(relation_names=["KNOWS"]) == [(alice, updated, bob)]