Are you sure you're not buying a 3 pound package? That's really the norm. A 3 pound package is probably somewhere between 9,000 and 12,000 bees....give or take.
As for splitting a package. My rookie opinion would be that it's challenging enough to get a package to survive, the last thing you would want to do is make it twice as hard for them. Not to mention, 1 package comes with 1 queen, so if you split them, you need another queen.