orphaned AVHDX Files after Hyper-V Guest Backup (Full/Inc)

Have you turned on the Microsoft Incremental method of backing up Hyper-V VMs (which I believe requires running Powershell scripts/commands) ?

I am not sure, but it is possible that this method does create extra files (which are needed for the next backup). As the basic description I have for this method is:

When a VM has MSFT Incremental Backup Support enabled.  A “checkpoint / snapshot” is created each time the VM is backed up.  Then when the next incremental backup runs, the only data that needs to be backed up is the data in the “checkpoint / snapshot”.  Then when the next incremental backup runs, another “checkpoint / snapshot” is created, and when that backup completes, the previous “checkpoint / snapshot” is merged into the parent “checkpoint / snapshot”.

The differences between MSFT and Symantec (BE Method) when it comes to Incremental backups of Hyper-V VMS are:

1. VMs with MSFT Incremental Backup Support enabled can’t be processed using DIFFERENTIAL backups.
2. VMs with MSFT Incremental Backup Support enabled can’t be backed up by more than one job.
3. VMs with MSFT Incremental Backup Support enabled will backup faster than VMs that don’t have it enabled.  However, the VM will perform somewhat slower as there is always a “checkpoint / snapshot” in effect.  How much slower the VM performs is dependent upon the VM.  VMs that have lots writes, will not notice much degradation, whereas VMs that are mainly reads, will notice some slow down.