Here is a feature request. When running an incremental backup that compares by timestamps, make a backup copy of the file or folder before overwriting with the newer version. Backup the older file with the same directory structure in a backup folder name with a timestamp.
Source: C:\Folder
C:\Folder\Sub\file.txt (newer)
Destination: D:\Backups
D:\Backups\Folder\Sub\file.txt (older)
Result:
D:\Backups\2007-10-18\Folder\Sub\file.txt (older)
D:\Backups\Folder\Sub\file.txt (newer)