diff --git a/addons/mail/models/mail_alias.py b/addons/mail/models/mail_alias.py
index af486717f00..4d6f38767d6 100644
--- a/addons/mail/models/mail_alias.py
+++ b/addons/mail/models/mail_alias.py
@@ -194,11 +194,21 @@ class Alias(models.Model):
         :param list sanitized_names: a list of names (considered as sanitized
           and ready to be sent to DB);
         """
+        valid_names = list(filter(None, sanitized_names))
+
+        # list itself should be unique obviously
+        seen = set()
+        dupes = [name for name in valid_names if name in seen or seen.add(name)]
+        if dupes:
+            raise UserError(
+                _('Email aliases %(alias_name)s cannot be used on several records at the same time. Please update records one by one.',
+                  alias_name=', '.join(dupes))
+            )
+
         catchall_alias = self.env['ir.config_parameter'].sudo().get_param('mail.catchall.alias')
         bounce_alias = self.env['ir.config_parameter'].sudo().get_param('mail.bounce.alias')
         alias_domain = self.env["ir.config_parameter"].sudo().get_param("mail.catchall.domain")
         valid_domain_aliases = filter(None, (bounce_alias, catchall_alias))
-        valid_names = list(filter(None, sanitized_names))
 
         # matches catchall or bounce alias
         for sanitized_name in sanitized_names:
diff --git a/addons/test_mail/tests/test_mail_alias.py b/addons/test_mail/tests/test_mail_alias.py
index cad05318fe8..53d0ac80e79 100644
--- a/addons/test_mail/tests/test_mail_alias.py
+++ b/addons/test_mail/tests/test_mail_alias.py
@@ -117,6 +117,14 @@ class TestMailAlias(TestMailAliasCommon):
                 'alias_model_id': alias_model_id,
                 'alias_name': 'unused.test.alias',
             })
+        with self.assertRaises(exceptions.UserError), self.cr.savepoint():
+            self.env['mail.alias'].create([
+                {
+                    'alias_model_id': alias_model_id,
+                    'alias_name': alias_name,
+                }
+                for alias_name in ('new.alias.1', 'new.alias.2', 'new.alias.1')
+            ])
         with self.assertRaises(psycopg2.errors.UniqueViolation), self.cr.savepoint(), mute_logger('odoo.sql_db'):
             new_mail_alias.copy({'alias_name': 'unused.test.alias'})
         with self.assertRaises(exceptions.UserError), self.cr.savepoint():