My back up scheme is this. I synchronize my laptop to my desktop and
then make up the desktop to an external drive.

I had been using the Seagate Backup manager on the Desktop which was
Windows XP. But the Seagate Backup Manager will not work on Windows 8.1

Could someone make some suggestions on back up software.

Criteria:

--Free if possible.

--Maintains at least two levels of previous files. ie it saves the
current file in the back up if there and replaces the file in the backup
with the current version on the desktop.

I have been using Syncback to sync the desktop and laptop. It can do
backups but don't believe it maintains the previous version of the files
in the back up.