Full backup has dependent full backups
In investigating why my backup volumes were running out of space, I came across a very strange problem, I had a Full Backup that wasn't being deleted by DLM because it had a dependent backup. Fair enough, except that the dependent backup, was itself a full backup!
In my environment, full backups of this age ( > 1 week old) should have no dependent backups at all, because diffs are configured to expire after 1 week.
But even if they weren't, how can a full backup be dependent on a full backup?
I'm running BE2012 with all hotfixes apart from 201596.
Any help understanding/fixing this problem would be very much appreciated!