Hi, I'm having the same problem.
I use this plugin on a lot of sites, but I few days ago I noticed that everyone of the sites using this plugin were using lots of serverspace. I'm talking several gigs more than the site really is.
When I go to the directory on the server where the backups are stored, I find up to 20 backups of really big sizes. Note that there are more backups than I scheduled for on the WP back-end. And I always use just one schedule.
I find files like this:
Which is corresponding to the list of backups I see in the WP back-end.
But also lots like these:
Again, i'm having this problem on several websites, all using this back-up plugin.
Thanks in advance.