Do you mean that you're putting STARS into two different TSYS objects?
Couple of things....
SCAN LISTS - Remember that with the 500 (unlike the PRO-96) a trunked system is not tied to a particular scanlist.You'll actually be scanning TGRP objects, and those can be assigned to any scanlist you like. They all know which TSYS object to connect to, and that TSYS object has no scanlist.
For example, much of northern West Virginia is on a STARS-like system of its own. (WVIRP) With one TSYS for that system and all the most likely CC's, I might put WV state TG's in SL#4, while putting Berkeley County TG's in SL#5 and Jefferson County TG's in SL#6. There's also a bunch of statewide EMS stuff that I might put into SL#10. So I have TG's for the same system all operating from the same TSYS object, but spread among at least 4 scanlists. The 500 allows this and does it well.
MULTIPLE TSYS OBJECTS - If you create additional TSYS objects to handle extra CC's, you also have to create a set of TGRP objects to monitor for each TSYS you have. STARS is only going to add more sites, and more talkgroups. Soon it'll outgrow your radio. I suggest putting all STARS stuff with a single TSYS object, and to only enter the CC freqs that you most frequently use. That leaves the rest of the CC spaces open for CC's that you might encounter on a trip somewhere. I keep all the STARS tower and their CC's in my GPS and can check my direction and distance from the nearest 4 towers simultaneously. If getting outside my stomping grounds, I can check the CC's for those sites (they appear on the GPS as well) and enter the ones I need.
In a recent trip to North Carolina, I used this setup with its VIPER system. I'd left blank spaces for CC's in my VIPER TSYS. While travelling down there, I selected CC's from sites displayed on my GPS, or simply entered CC's that I found in search mode and analyzed in tune mode.
MULTIPLE V-SCANNERS
I don't know about you, but I use multiple V-scanner files as I move around. I have a normal one for Richmond, plus extra ones for the areas around Petersburg, Lynchburg, Roanoke, Fredercksburg, DC, Charlottesville, Winchester, Staunton, etc. In each of those, I program the most likely STARS freqs and TG's as well as all the local stuff. This lets me take a pretty long trip without the need for a lot of keystrokes. This is how I solved the dilemma of STARS and all its different CC's.
It's also easy to find STARS CC's via search mode anywhere that's in range of the system. That's how we found most of the CCs that are in the database.
The multiple V-scanners is the way to go. With 1852 objects in 20 scanlists, you can cover a lot of territory with each one.
Just my 2 cents...
73/Allen (N4JRI)