Re: Yet another First Time Brisket! QuestionCooking them both at once won't effect the time each one takes to cook much if any since they are so small especially. The best way by far is to monitor the internal temp of each one. Do you have meat thermometers to do this? Personally, I don't think time means much at all with briskets and butts more so than anything.
If you have thermos take them up to around 165-170 then foil and continue to 190-195 internal. Rest them wrapped in towels in a cooler for at least an hour if possible. When you foil them put a little apple juice, beer, or whatever liquid you spray/mop with in the foil before wrapping them. I've heard of some folks even using coffee.
If you don't have thermos you can check them with a fork or probe of some kind. When it slides in with virtually no resistance they should be ready. I would still let them rest an hour to re-distribute juices with the second method.
Welcome to SMF Fred!!! When you get a chance, pop up to Roll Call and introduce yourself.