As designed, no. Server backup in V1 doesn't have the ability to back up the client backup database. (The next version
will have that ability.)
However, you can either do so manually, using the procedure Microsoft has outlined in their Home Computer Backup and Restore technical brief, or (better) install the Backup DataBase Backup (BDBB) add-in which automates the same process for you.
I'm not on the WHS team, I just post a lot. :)