Symantec does not support multi-version manager replication scenarios. Database schemas can change from version to version, and database corruption could occur if the schemas do not match. All Symantec Endpoint Protection sites that replicate should be running the same version.
From Maintenance Release 4 (11.0.4000.2295) onwards, all Symantec Endpoint Protection Managers will check database versions before setting up replication agreements with remote sites.
For details on how to migrate replicated sites, please review the migration Knowledge Base article pertaining to the release to which you are migrating up.
'Migrating to Symantec Endpoint Protection 11.0 RU5', KB document ID: 2009090313483348