Thanks for reaching out to us. We are happy to assist. When you have two boxes, and are using one router, you have to make sure that both are using a separate port. This of course is what allows the Slingbox to view remotely. You mentioned that the device automatically went to 5002. We actually have a few other ports that we can switch too. ie: 5001, 8080, 443. It is possible that the first Slingbox is already set to port 5002. It might be as simple as going in and changing out the ports.
Below we have included a link tha will show you how to set up portforwarding on your router:
How to use the Slingbox Network Setup Assistant to help configure your router
Hope this helps:
The Slingbox Moderation Team