Sorry - I thought it did. As long as there's plenty of airspace around the butts, they should cook like a single, or maybe a little longer. I think bumping the temp to 240 would be a good idea (to account for the extra mass), and allow yourself an extra hour, you should be OK. But - it depends on the butts, too! You can never tell how long it will take; I average around 1 hour per pound on the ones that I buy, but some are closer to 2 hours per pound. If you buy them from the same place as singles you have done, you should be able to use that as a rough estimate. For planning, I'd probably allow 2 hours per pound (of the biggest one), and probe the smallest one. You can always wrap/rest in the cooler if they're done ahead of schedule. You can also hold them in the smoker @ 140.