Multi system fictions are rare because it can be a PITA to set them up. Multiple factions inside a single system are far more common. For example, Kurt's Twin Moons campaign here:
http://aurora2.pentarch.org/index.php?board=39.0and of course Steve's Trans-Newtonian campaign here:
http://aurora2.pentarch.org/index.php?board=16.0as well as Steve's Solarian Empires campaign here:
http://aurora2.pentarch.org/index.php?board=198.0I'm sure there are others, those are off the top of my head.
For multi system, it's easier if you have one faction start in Sol and then use SM to create other systems until you find a suitable one and then create a new race empire in that one. But the problem is that you cannot guarantee a JP connection between the two. So if you create both at game start, they might not get into contact for decades. Or they might be right next door to each other. And there is no way around this. So a better idea might be to just play one faction in Sol, and then when that faction finds a nice looking system at a suitable distance from Earth, you manually create a New Race in there and THEN start running a multi faction game.
In fact, that's how I'm planning to run my C# multi-faction games: having multiple factions in Sol and then introducing new alien factions as they explore the galaxy, in addition to NPRs and spoilers.