Check the default settings for course backups. Think, by default, a backup file name would include the course ID and the course short-name as well as a date/time stamp in the filename itself.
So the filename of a backup might look like:
backup-moodle2-course-1402-moodle_online_teaching_and_learning-20160725-1323.mbz
Think it would be rare to set the backup file name to backup.mbz but guess someone could. In your query include 'contenthash'. That's really the path/location of the backupfile if saved back into filedir. If those 107 records have the same contenthash value it's a single file ... not 107 individual backup files.
Backups could be made as no user backups ... which means student work would not be included in the backups. Heck, had one site that hadn't re-set a multimedia course in almost three years and it's backup reached 139Gig. This to say, yes ... backups of courses can reach Gig range in a K12 Moodle easily and in a short time frame as well.
Don't understand the reason for the references to:
component: tool_recyclebin
filearea: tool_recyclebin
Is your space issue ... ie 0 bytes free ... resolved?'spirit of sharing', Ken