I know that some babies do sleep that length of time at that age, but they are more the exception than the rule. Both my dd's did long sleeps for a short while around that age, but it didn't last. Then started properly sleeping through around 4m (7pm-7am with a 10pm dream feed).
Strategies to help them go longer at night - do cluster feeds in the evenings (to 'tank them up'!), and a dream feed before you go to bed (don't actually wake them for this). In my experience the more well rested the baby is, the better they sleep at night. So when the day sleeping started going well, that's when the night sleeping got better. We used a pacifier with dd2, and night sleep got much better once we weaned her off it at 4m.
I don't have any experience with twins, but there is a board for multiples - maybe someone there can help you with that part of your question.