While editing audio clips is usually nondestructive, this is generally not the case for MIDI clips. For instance, if a MIDI clip resides in just one track at a single location, editing for that clip is destructive. This means that altering the pitch, duration, or placement of notes in Notes view permanently alters the clip.

However, if the Mirror MIDI Editing option is disabled, when editing a MIDI clip that appears elsewhere in the project (either on the same track at another location or in a different track), editing is nondestructive and creates a new auto-created clip. To go back to the previous material, drag the original clip from the Clips List.