This is to prevent the case where audio later in the file (maybe defined as a region and used somewhere else in the session) could get overwritten.- Imagine you've edited a contiguous audio file into 3 regions: [1] [2] [3]- You move region [2] leaving a space: [1] [space] [3] [2]- Then you destructively record from region [1] through the [space] and in to region [3]. You still want to have region [2] unchanged. Since region [2] actually exists on the disk where the [space] is, Pro Tools creates a new audio file so that region [2] is not recorded over.