In this scenario it is not possible to restore the user account back to the original domain, Domain A.
The reason for this is that during the migration process from Domain A to Domain B there is no tombstone generated in Domain A for the migrated object.
Unlike when a user account is deleted, migration of an account to a new/alternate domain does not leave a tombstone in the originating domain.
Recovery Manager cannot restore any Active Directory object without a tombstone.
