I think it is just a matter of preference and fly selection. There are numerous setups that I have seen printed. The main issue in my view is focusing on the intention of throwing multiple setups. Most people try to address multiple levels of a hatch. Others do it to give them more opportunities to catch fish by addressing two different flies. However; I have found that this setup does not work well for me on tailwaters. It usually detracts from my presentation and it is more visible to trout. Plus, I always end up getting wind knots and tangles from my wild casts.