Duplication speed with staging / parallel process

Hi all

I've a question regarding duplication speed between media servers. Our setup is as follows:

Clients do backup to different media server, storage is basic disk. This usually happens during night time.

At each storage unit there is a staging schedule defined, which will duplicate all images to another media server with similar storage (same size, same type, same raid level etc) during day time. This works fine, dupliction is started according to schedule, and according to number of maximum concurrent jobs. On source server, the one sending images to destination server, many processes of bpdm are started, all with network activity towards destination server. On destination side however there's a single pbx_exchange process started receiving all this traffic and storing it to disk.

Now my question is as follows: both source and destination server are connected to each other with dedicated 10Gpbs links, but with duplication process we're unable to reach speeds beyond 2Gbps. First we've checked server and storage itself, with multithreaded file copy from source to destination storage (robocopy images from source to destination) we're able to reach much higher speeds, up to 8Gbps over smb file share. Is there a setting which allows more parallel processes or streams to be run with duplication? On source side I see many number of bpdm processes, but just a single one on destination.

NetBackup master, media (both source and destionation):

OS: Windows 2008 R2

NetBackup: 7.6

Thanks in advance for any insight

Christian