VDP documentation says that VDPa supports replication to VDPa?

I know that VDP 5.5 can replicate to Avamar,  but VDPa is still version 5.1.  VDPa 5.1 does not have replicationcapabilities,  but the VDP 5.5 doc says that it does?

What gives?

Thanks,

-MattG