A recommended Biztalk best practice for performance is to have a separate Tracking Host . So when you add a separate Tracking host , you might encounter this scenario
Event Type: Error
Event Source: BAM EventBus Service
Event Category: None
Event ID: 25
Time: 1:53:25 AM
Either another TDDS is processing the same data or there is an orphaned session in SQL server holding TDDS lock.EXECUTE permission denied on object 'TDDS_Lock', database 'BizTalkDTADb', owner 'dbo'. SQLServer: mysql, Database: BizTalkDTADb.
Soln: This means that your one of your Hosts other than the Tracking Host has the Host Tracking property Checked . Uncheck this and you should be all set