BESR sees the drive itself, and will create a backup the the drive, regardless of the cartridge in the drive. Thus, it is necessary to make sure the cartridge has plenty of room before inserting it the next morning. Because of the rotation, and if only 1 job is set up, the chain of backups is not maintained, and the automatic removal of the previous image. To remedy this, create 2 separate jobs (i.e. M,W,F) and use the same cartdige for those days, and T,TH,S for the next. Since you are not breaking the chain by using the same cartridge for that respective day, the previous image(s) will be seen and purged if you have the job setup to do that.