First.. sorry for my english... i use spanish.
Yes.. you can put 2 DVR system in same network. You must setup different IP and Port for each DVR. Then forwarding Port corresponding each IP in the router for monitoring in Internet. Example:
First DVR... IP: 192.168.1.10 Port 4080
Second DVR... IP: 192.168.1.11 Port 4090
for Access you must key 192.168.1.10:4080 or
192.168.1.11:4090
I hope this note help you.