As the rr database is structured now, a system should only contain one System ID. Consider if you were searching for a system in the database by System ID - you'd want the site you're looking for to show up. I suppose you could submit a request to modify the database structure, but I think it's that way for a reason.
Also consider that talkgroups may be "re-used" from one system to the next. 4096 on one system is probably going to be labelled differently on one system from another. I don't think we need a bunch of talkgroups listed multiple times, each one with a different label. Imagine trying to use that list when using the data import utility on newer scanner model's programming software.
The use of separate system IDs is a choice Duke Energy has made when constructing its radio systems. The networked system is called Smartzone, and you gave some examples of Smartzone in your last post. A Smartzone system is more expensive (you have to have a Zone Controller to link the sites together as well as the actual link between systems, either phone lines, microwave or IP) and it can be harder to manage.
Brian
Brian