This is a really basic mod that just duplicates the Shattered Empire faction .xml and makes the copy permanently hostile. The second faction *isn't intended* have access to the first's quests, titles, or anything of the sort (since it shouldn't need them).
There might be any number of weird interactions, please notify me if the second faction does anything you think it shouldn't down below.
1.1:
The Non-Hostile version allows you to pursue both factions' favor, if you want that. It won't increase the number of quests given, but maybe you can have some internal politics for roleplay. Up to you. Do NOT use both at the same time - there shouldn't be any major breakages but only one will work.
Also probably only useful in 1.1:
If you wanna see both empires start slinging psionics around (like they ought to!) check out Powerful Psycast AI! Two Families includes a patch for incorporating psykers into the second Empire's lineup too.
Have fun!