diff --git a/src/pretix/base/migrations/0299_fixup_eventmetaproperties.py b/src/pretix/base/migrations/0299_fixup_eventmetaproperties.py
index d3b4440b48..20ceee6a21 100644
--- a/src/pretix/base/migrations/0299_fixup_eventmetaproperties.py
+++ b/src/pretix/base/migrations/0299_fixup_eventmetaproperties.py
@@ -1,7 +1,7 @@
 # Generated by Django 5.2.12 on 2026-04-28 11:34
 import logging
 
-from django.db import migrations
+from django.db import IntegrityError, migrations, transaction
 from django.db.models import Count, F
 
 logger = logging.getLogger(__name__)
@@ -17,6 +17,10 @@ def fix_cross_organizer_eventmetavalues(apps, schema_editor):
         try:
             emv.property = emv.event.organizer.meta_properties.filter(name=emv.property.name).first()
             logger.info(f'  found existing EventMetaProperty in {emv.event.organizer.slug}')
+            if EventMetaValue.objects.filter(event=emv.event, property=emv.property).exists():
+                logger.info(f'  EventMetaValue with property in correct organizer already exists, deleting the cross-organizer one')
+                emv.delete()
+                continue
         except EventMetaProperty.DoesNotExist:
             meta_prop = emv.property
             meta_prop.pk = None
@@ -24,7 +28,6 @@ def fix_cross_organizer_eventmetavalues(apps, schema_editor):
             meta_prop.save(force_insert=True)
             logger.info(f'  created new EventMetaProperty')
             emv.property = meta_prop
-        # TODO: how to handle new duplicates in EventMetaValue.property
         logger.info(f'  after: {emv.property.name}({emv.property.id}@{emv.property.organizer.slug}) = {emv.value}')
         emv.save()
 
@@ -42,17 +45,28 @@ def make_eventmetaproperties_unique(apps, schema_editor):
         target = props[0]
         invalid = props[1:]
 
-        # TODO: how to handle new duplicates in EventMetaValue.property
-        affected = EventMetaValue.objects.filter(
-            event__organizer=dup['organizer'], property__in=invalid
-        ).update(
-            property=target
-        )
-        logger.info(f'  Switching {affected} value(s) over to {target.name}({target.id}@{target.organizer.slug})')
+        try:
+            with transaction.atomic():
+                affected = EventMetaValue.objects.filter(
+                    event__organizer=dup['organizer'], property__in=invalid
+                ).update(
+                    property=target
+                )
+                logger.info(f'  Switching {affected} value(s) over to {target.name}({target.id}@{target.organizer.slug})')
 
-        for prop in invalid:
-            logger.info(f'  Deleting {prop.name}({prop.id}@{prop.organizer.slug})')
-            prop.delete()
+        except IntegrityError as e:
+            logger.info(f'  Failed to switch all value(s) over to {target.name}({target.id}@{target.organizer.slug})')
+            logger.info(f'  {e}')
+            for prop in invalid:
+                newname = f'{prop.name}_DUPLICATE_{prop.id}'
+                logger.info(f'  Renaming {prop.name}({prop.id}@{prop.organizer.slug}) to {newname}({prop.id}@{prop.organizer.slug})')
+                prop.name = newname
+                prop.save()
+
+        else:
+            for prop in invalid:
+                logger.info(f'  Deleting {prop.name}({prop.id}@{prop.organizer.slug})')
+                prop.delete()
 
 
 class Migration(migrations.Migration):