They don't claim to have invented CDC, or FastCDC, they just made and are sharing a useful implementation of it.

And if that Tarsnap presentation is from 2013, and FastCDC was published in 2016 [1] according to Wikipedia [2], then presumably Tarsnap didn't invent FastCDC either.

[1] https://www.usenix.org/system/files/conference/atc16/atc16-p...

[2] https://en.wikipedia.org/wiki/Rolling_hash#Gear_fingerprint_...