Do I backup Hyper-VM VM's AND the Data Drive they are on with Windows Server Backup?

I just started running a backup using Windows Server Backup 2012 with Hyper-V. 

My VM's are all located on my D: partition which brings me to a confusing point.

When I use windows server backup I can select my hyper-v VM's to backup and (separately) I can select the D: data drive in which they reside.  My questions is, should I be doing that? or that over redundant?

Thanks in advance!

Luke