What blu said. And is probably why more of us are switching to singles than for the other reasons. Much easier to connect the two systems together, whether with an H, or X crossover when they're on the same side of the vehicle. And at that point you might as well make the decision on whether to stick with dual, or just go single and be done with it.
If single, you can use a merge before the muffler instead of an H, or just use a 2-into-1 muffler designed just for this sort of thing in the first place. A compromise might be a 2-into-2 muffler. The two outlets let you have your dual look, dual-ish sound, and simpler plumbing with just a single muffler.
Lots of choices out there.
I'm still torn. Love my true duals with crossover all on the passenger side, but know that it will be easier to plumb (and cheaper!) to just use a good single.
Paul