Backups not counted properly

I configured the plugin to keep 7 database backups and 3 full backups.

However, when I open the backup tool in the admin interface for the first time, it displays a wrong count of backups. The navigation bar for the schedules is off by one. It claims to have 8 database backups and 4 full backups.

Just the number after the schedule’s name is wrong and the table’s caption as well. The actual number of backups in the table, however, is correct.