Backup SQL Server with VMware

The VMs I run SQL Server on are regularly backed up by the VMware backup tool. I would prefer not to use this backup solution but I have no choice but to cope with it. The problem I've come up across is the fact that every time the VM backup us ran, SQL Server thinks it has performed a full backup of the databases to a virtual device (physical_device_name = GUID). I can see those backups in msdb (they are copy_only backups so I don't have to worry). Do you know why it works this way? Is VMware aware of SQL Server existence? Or maybe SQL Server has wrong data in msdb? Can I run into any problems with that solution (other than trying to restore the DB from the virtual device)?