Twins! And cluster feeding

My fraternal twins were born on November 22nd they are 3 months old they are still cluster feeding about every 2 - 2-1/2 hrs. Is this normal?  They have a nanny who comes by daily in the morning- afternoon and plays with them and talks to them. However I feel they sleep a lot during the day. Culturally I have heard to keep them up throughout the day. But everything I read says to allow them to sleep if that's what they like. They don't have much of a schedule right now but have noticed that they do the most sleeping from 10pm-2am at night ( 4 hrs). Any tips out there from twin mommies?