diff --git a/applications/portal/backend/api/services/antibody_service.py b/applications/portal/backend/api/services/antibody_service.py
index f0f345e1..95aae8f6 100644
--- a/applications/portal/backend/api/services/antibody_service.py
+++ b/applications/portal/backend/api/services/antibody_service.py
@@ -46,6 +46,9 @@ def create_antibody(body: AddAntibodyDTO, userid: str) -> AntibodyDTO:
     antibody.uid = userid
     antibody.save()
 
+    if antibody.get_duplicate():
+        raise DuplicatedAntibody(antibody_mapper.to_dto(antibody))
+
     return antibody_mapper.to_dto(antibody)
 
 
diff --git a/applications/portal/backend/api/tests/test_antibodies.py b/applications/portal/backend/api/tests/test_antibodies.py
index 80c83d94..4cb88388 100644
--- a/applications/portal/backend/api/tests/test_antibodies.py
+++ b/applications/portal/backend/api/tests/test_antibodies.py
@@ -3,6 +3,7 @@
 from api.services.search_service import fts_antibodies
 from api.models import Vendor, VendorDomain, VendorSynonym
 from api.repositories.maintainance import refresh_search_view
+from api.utilities.exceptions import DuplicatedAntibody
 
 from openapi.models import (
     AddAntibody as AddAntibodyDTO,
@@ -108,14 +109,14 @@ def test_create(self):
         a.save()
 
         duplicated = AddAntibodyDTO(**example_ab)
-        # duplicated.vendorName = "My vendor synonym" # should keep the same vendor and add a synonym
-        da = create_antibody(duplicated, "bbb")
-
-        assert da.accession != da.abId
-        assert da.abId == ab.abId
-        assert da.status == Status.QUEUE
-        assert da.vendorId == ab.vendorId
-        assert da.vendorName == "My vendorname"
+        with self.assertRaises(DuplicatedAntibody) as exc:
+            create_antibody(duplicated, "bbb")
+
+        da = exc.exception.antibody
+        self.assertEqual(da.abId, ab.abId)
+        self.assertEqual(da.status, Status.QUEUE)
+        self.assertEqual(da.vendorId, ab.vendorId)
+        self.assertEqual(da.vendorName, "My vendorname")
 
         assert VendorDomain.objects.all().count() == 2
         assert Vendor.objects.all().count() == 1