Hi mummy! congrats on your twins! I think either you try feed them slowly cause if baby is anxious or irritated cause of feeding delays, will sometimes cause them to choke etc. However, if multiple times they vomit like Merlion style and even out from the nose, best you go check with your PD. sometimes scared that baby is lactose intolerant. Go check and be safe than sorry!
observe how many days and is it after every feed? if because didnt burp then u can try youtube on how to burp. they will teach u many ways. if u have burp but still experience this then visit PD asap.