How much time you want to take will determine at what temp you want to smoke those butts. Two 8 lbs butts will take the same amount of time as one 8 lb butt. I've done butts at every temp possible on my smoker.
Low n slow: At 225F you're looking 12-16 hours, no wrapping.
Your electric smoker most likely has a max temp of 275F. You can cut your max smoking time to 8-12 hours running at 275F, no wrapping.
You can definitely finish in 7-8 hours if you smoke them at 275F until the IT is 175-180F, then wrap them in a roasting pan with a cup of apple juice and put them in your kitchen oven at 350F until the IT is 203-205F. You'll still get great bark and they'll be done quicker.
In all cases above they need to rest a couple hours before you pull the meat apart. Take a taste and adjust the flavor profile with a little more rub, finishing sauce, BBQ sauce, apple juice, whatever you want to use.
I prefer to smoke mine a day or two before I'm going to serve it. I don't inject but I do save the wrapping juices, let the juices separate overnight in the fridge, discard the fat and put the gelatin back in the pulled meat the next day. I think PP tastes better the next day but many folks prefer it right off the smoker.