Duplication Job of 2008 R2 AD Server to Dedup device runs very slow

I am backing up a Windows 2008 R2  AD server using Backup Exec 2010 R3 SP2 with all the latest hotfixes.  The Backup process runs at an acceptable speed (18GB @ 15m) but the duplication job (which is duplicating to a BE deduplication device) runs very slow (same 18GB @ 2h45m).  This also occurs on two other AD servers (seperate jobs).  All other jobs perform fine.