New machine, Same name (DPM protection error)

Environment:

We have a Cluster of 3 VMHost, Host A,B,C.

We use DPM 2012 R2 to backup the VM host and the Cluster as a whole.

Issue: VMHost A failed, so we replaced with a different model machine (D). We change the name of VMHost D to the same name of VMHost A. DPM is now failing to backup our VM even though they are in different VMHost in the cluster.

Question: Why doesn't DPM register the new machine with the same name as part of the cluster?
How do I handle the current machines that are no longer being back up?