[golfgod04]

It seems like you're really asking what styles this might work best with, rather than going after seeing the differences between something like two English yeasts.

IMO, there is no real preferred style for splitting a batch this way but the darker/roastier you go your options become more limited.  If your base wort is a stout, you're really going to wind up with two stouts even if you pitch one with a Belgian yeast.  If your base wort is very light, you could do a saison and a pilsner.  Amber beer you could do a brown ale and a dubble. Options are pretty much endless.  Last time I planned to do this route, my two beers were a pils and a tripel.  The tripel would have had sugar additions to the fermenter, but other than that the base wort would have been the same.

Now that I'm thinking about it, a split batch quad and dopplebock could be fun.

That is more of what I was asking. I wasn't clear.  Is there another option to go with tripel?

[golfgod04]

you can also maximize the difference by adding an additional adjunct to one portion. Belgian or British syrups can add a lot of character and can be added right to the fermenter. as does molasses

Honey and Maple syrup can also be added to the fermenter. they lend a much more subtle character that is easily lost in stronger flavored beers.

Good idea thanks

[santoch]

American Wheat and German Hefeweizen can be done with the same wort and a Kolsch and Hefeweizen yeast.
Plus, you can do things with hop extracts, sinnamar, and dry hops to make the American wheat a bit more complex if you are so inclined.