When I had Mozy I used SyncToy to sync with a public folder on one of my PCs from all the others but with all the music and pics from the family PCs I was at 300 GBs - no doubt lots of dupes but Mozy changed their "unlimited" backup and I just did not renew - just shelved the public disk for the moment ...
I'd looked at various sync programs out there to automatically back up the various PCs (My Docs, My Pics, Outlook etc. but fire, flood, asteroid, etc. risks meant no offsite backup. Sigh! ;-)
Well, you’d have to delete the previous version first before a new copy.
If you want to automate the backup, I like a free program called Cobian (version 9). It’s basically just an automated copier. You specify the source folders, the destination folder, and the number of different copies to keep on the backup device before they get rolled off. I never allow it to run all the time. I specify manual backups and just start it when I want a backup made, and then kill it.