DPM 2012 - Backup Exchange 2013 (DAG)

Hi,

I have 4 server in Exchange 2013 farm configured DAG.

I have 20 DB

In DAG configuration all DB is on each server, but only one is active.

when I want to backup those DB, what is the best option:

1) create PG for every server and backup all DB on the server.

or

2) Create one PG and backup all DB in all servers.

or there is a better option?

Thanks,

LIOR