Nothing special needs to be done at this point, except be prepared that twins rarely survive.
It's also possible that when you candled, you saw butt and head, and thought it was 2 different ones. They look kinda squirrely during those mid-incubation days, depending on how they are laying.
If they make it all the way to lockdown and you determine there really are twins, some assistance may be required, if you want to help them hatch. usually they are laying ying-yang position, which means that one gets the air cell, the other doesn't, so the one with its head near the non-air cell end would likely need help.
You can read up on assisted hatches if you want, to get a little prepared and decide if it's something you want to do, if and when the time comes..
good luck!