Create Backup ⌃B

Create a backup copy of the current audio file. The Audio File Editor performs destructive edits which cannot be “undone”. Reverting to the backup copy is the only way to undo the edits.

The Project Audio Browser has a command — Backup File(s) — which uses the same keyboard mapping. Files backed up have the same ‘.dup’ extension as they do when backed up in the Audio File Editor.

Backup audio files in the Audio File Editor in Logic Pro — Apple Support

In Logic Pro, choose Audio File > Create Backup from the Audio File Editor menu bar (or press Control-B).
A copy of the audio file (with the extension .dup) is created in the same folder as the source file.

The Project Audio Browser in Logic Pro — Apple Support

The Project Audio Browser shows all audio files and regions that have been added to or recorded in your project, whether or not they are used in the Tracks area. Regions shown in the Project Audio Browser that are not used in the Tracks area are indicated in red.