diff --git a/managers/sfrRecord.py b/managers/sfrRecord.py
index 1db4374934..536631706e 100644
--- a/managers/sfrRecord.py
+++ b/managers/sfrRecord.py
@@ -3,7 +3,7 @@
 import json
 from Levenshtein import jaro_winkler
 import pycountry
-import re
+import re, copy
 from uuid import uuid4
 
 from model import Work, Edition, Item, Identifier, Link, Rights
@@ -39,7 +39,7 @@ def mergeRecords(self):
 
         matchedWorks.sort(key=lambda x: x[1])
 
-        allIdentifiers = self.work.identifiers
+        allIdentifiers = copy.deepcopy(self.work.identifiers)
 
         for edition in self.work.editions:
             allIdentifiers.extend(edition.identifiers)
diff --git a/migrations/versions/cc966d5a6ca0_add_unique_constraint_to_work_.py b/migrations/versions/cc966d5a6ca0_add_unique_constraint_to_work_.py
new file mode 100644
index 0000000000..c9558b78fb
--- /dev/null
+++ b/migrations/versions/cc966d5a6ca0_add_unique_constraint_to_work_.py
@@ -0,0 +1,24 @@
+"""add unique constraint to work_identifiers table
+
+Revision ID: cc966d5a6ca0
+Revises: 54e57fb2e1c6
+Create Date: 2024-09-05 16:48:16.569654
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = 'cc966d5a6ca0'
+down_revision = '54e57fb2e1c6'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    op.create_unique_constraint('unique_work_identifier', 'work_identifiers', ['work_id', 'identifier_id'])
+
+
+def downgrade():
+     op.drop_constraint('unique_work_identifier', 'work_identifiers', type_='unique')
diff --git a/model/postgres/work.py b/model/postgres/work.py
index 2fd255a6cc..603633c159 100644
--- a/model/postgres/work.py
+++ b/model/postgres/work.py
@@ -6,8 +6,8 @@
 from .base import Base, Core
 
 WORK_IDENTIFIERS = Table('work_identifiers', Base.metadata,
-    Column('work_id', Integer, ForeignKey('works.id', ondelete='CASCADE')),
-    Column('identifier_id', Integer, ForeignKey('identifiers.id', ondelete='CASCADE'))
+    Column('work_id', Integer, ForeignKey('works.id', ondelete='CASCADE'), unique=True),
+    Column('identifier_id', Integer, ForeignKey('identifiers.id', ondelete='CASCADE'), unique=True)
 )
 
 WORK_RIGHTS = Table('work_rights', Base.metadata,
diff --git a/processes/sfrCluster.py b/processes/sfrCluster.py
index 6a54461a0c..0b2889530e 100644
--- a/processes/sfrCluster.py
+++ b/processes/sfrCluster.py
@@ -1,7 +1,7 @@
 from datetime import datetime, timedelta, timezone
 from math import ceil
 import re
-from sqlalchemy.exc import DataError
+from sqlalchemy.exc import DataError, IntegrityError
 from sqlalchemy.orm.exc import StaleDataError
 
 from .core import CoreProcess
@@ -101,7 +101,7 @@ def clusterRecord(self, rec):
 
         try:
             self.session.flush()
-        except (DataError, StaleDataError) as e:
+        except Exception as e:
             self.session.rollback()
             logger.error('Unable to cluster {}'.format(rec))
             logger.debug(e)