N2WS supports backup objects from multiple regions in one policy. In most cases, it would probably not be the best practice, but sometimes it is useful. When you choose a target region for DR, DR will copy all the backup objects from the policy which are not already in this region to that region. For example, if you back up an instance in Virginia and an instance in North California, and you choose N. California as a target region, only the snapshots of the Virginia regions will be copied to California. So, you can potentially implement a mutual DR policy: choose Virginia and N. California as target regions and the Virginia instance will be copied to N. California and vice versa. This can come in handy if there is a problem or an outage in one of these regions. You can always recover the instance in the other region.