diff --git a/conda-store-server/conda_store_server/storage.py b/conda-store-server/conda_store_server/storage.py
index 2e37ec6d7..4efb4765f 100644
--- a/conda-store-server/conda_store_server/storage.py
+++ b/conda-store-server/conda_store_server/storage.py
@@ -21,10 +21,17 @@ def fset(
         filename: str,
         artifact_type: schema.BuildArtifactType,
     ):
-        db.add(
-            orm.BuildArtifact(build_id=build_id, key=key, artifact_type=artifact_type)
+        ba = orm.BuildArtifact
+        exists = (
+            db.query(ba)
+            .filter(ba.build_id == build_id)
+            .filter(ba.key == key)
+            .filter(ba.artifact_type == artifact_type)
+            .first()
         )
-        db.commit()
+        if not exists:
+            db.add(ba(build_id=build_id, key=key, artifact_type=artifact_type))
+            db.commit()
 
     def set(
         self,
@@ -34,10 +41,17 @@ def set(
         value: bytes,
         artifact_type: schema.BuildArtifactType,
     ):
-        db.add(
-            orm.BuildArtifact(build_id=build_id, key=key, artifact_type=artifact_type)
+        ba = orm.BuildArtifact
+        exists = (
+            db.query(ba)
+            .filter(ba.build_id == build_id)
+            .filter(ba.key == key)
+            .filter(ba.artifact_type == artifact_type)
+            .first()
         )
-        db.commit()
+        if not exists:
+            db.add(ba(build_id=build_id, key=key, artifact_type=artifact_type))
+            db.commit()
 
     def get(self, key: str):
         raise NotImplementedError()