Whenever an Anima scene is saved, a backup of that scene is also saved in the same Anima project folder.
The backup scene files have the same name but a different extension. In the backup files, the standard "ani" extension is replaced by a number sequence that starts at "001" and is increased on every file save, always keeping the most recent one at the lower number.
You can easily restore any older saved scene by manually renaming any backup file to a new name with the *.ani extension.