Is there An open source de duplication backup solution? [closed]

Something simple like rsnapshot may do what you want. It doesn't sound like you want what's traditionally referred to as deduplication. The synthetic full backup functionality using hard-links that rsnapshot provides sounds like exactly what you're asking for.

(On the traditional deduplication front you may want to look at the Opendedup project as a starting point. It's the most complete open source data deduplication project that I've seen. It uses a custom filesystem (SDFS) as the basis of its functionality. I tend to think that this isn't want you're looking for, but in the interests of completeness I mention it here.)

Bacula writing to a ZFS filesystem that has de-duplication turned on, then write the snapshot from that host to a remote host with ZFS and apply that transaction log to that filesystem.