Virtual Machine is unavailable and will ... - Veeam Software
https://www.veeam.com/kb129915.10.2011 · Veeam Backup & Replication tracks every VMware VM by its unique MoRef ID. If the MoRef ID for a machine changes, it is treated by Veeam Backup & Replication as a different machine. If the VM is added to a job where it was backed up previously, the existing restore point chain will not continue with the re-added VM because the VM now has a different MoRef ID.