I have that same reactor (using carbon and PhosGuard). On the new system I plan to do carbon and GFO.
The idea of two separate reactors is good for the reason that Bud stated... but it can be done with this reactor. Mine doesn't have the bracket, so it is easy to see that the canisters are linked with large John Guest fittings and a short piece of tubing. You could simply take out the middle piece, and add two longer pieces (one exit for canister one, one entrance for canister two) and run them on two separate pumps or off a manifold. Of course, this may only be worth the trouble if, like me, you already have the dual. If I were buying new, I'd get two single reactors.