I'm not brave enough to try twins yet, I have a single sim mom, artist, who I had adopt a baby, then when she aged up to toddler I adopted a toddler. That has been fun, one needs a diaper change as the other wants to be fed. One is going to bed as the other wakes up and needs to be fed. In between trying to keep them clean, happy and fed your sim is trying to get some rest, fed and clean herself, plus painting pictures to have an income.
If you are new to sims, as I am, I would suggest you try with one. Then later, after you feel comfortable in raising that baby, you can try for twins.
If you have played othter sim games and know your way around, then I wish you luck, it can be a lot of work.