I had twins. They are 12 now.
Naps at that age were good. Quiet time after lunch. I think twins get a lot more stimulation from each other so they can get tired out more quickly.
Stay outside as much as possible, the screaming sounds less loud.
Play whisper games, tiptoeing around, lots of role play around sleeping and being patient and waiting for things, like plants growing, clouds moving across sky, worms wriggling slowly across floor, bread rising. Remind them of slow stuff so that they don't feel everything has to happen fast, right now.
A lot of screaming in our house seemed to be related to needing to pee, and holding on too long 
could that be one of the things that is making them more reactive than usual?
Also control issues, impatience can be to do with not quite being sure what the routine is, and whether they know or can control what is happening next in the day? Sugar lows? Regular snacks at least 5 meals a day including elevenses and tea break.
Downtime in general, self regulation, might include playing by themselves with soft toys in very quiet non exciting ways.
Play which soothes like pouring water on things (outside?) sitting in the bath in the daytime and just playing with watering cans and plastic figures there. Playdough.
Reducing the number of events and transitions in the day, packing less in. Meals simple and predictable, lunch could be bread and butter and cheese and an apple or pasta with butter and ham and a carrot stick.
Singingnursery rhymes so they can use their voices and express energy but regulate at same time.
Send one twin off on a playdate!
I remember feeling at the end of my tether quite often, especially at teatime.I remember once they both used to dance on the table, I used to feel like Nurse Ratchet. Now I look back and think, uh they were toddlers why did I feel so persecuted by them????? It is a bit of a mindset.