By default, MIXO creates backups before importing any XML or NML file, and in some cases before exporting to certain software.
IMPORTS: Backups are saved for all XML and NML files you import.
EXPORTS: Due to overwriting existing files, backups are also saved for Serato and VDJ exports, so that you can restore your old library if you need to.
Backups are saved to ~/Music/MIXO/Backups
By default, MIXO saves 5 backups for each software to mitigate the amount of space they use on your computer. However, you can increase this as required.