BE2012 Old B2D IMG folders taking up space on HDD

Hi,

I've recently run out of space on the Back-to-Disk HDD and am looking within the B2D folder. There are some folders...ÍMG001394', ÍMG001395' etc that are from three weeks ago when the backup retention period for the B2D jobs are only 6 days. We do however have duplicate to tap jobs which have 'media set: keep data for 3 weeks'. When I look into the jobs and the backup sets I can't find any B2D sets older than 6 days. Basically I want to be able to find out what jobs those IMG folders refer to, why they are there and why BE isn't deleting/overwriting them.

Many Thanks.