I have 2 yr old twin boys and we didn't find out they were boys until we had them. My advise is:
Pick 4 names you both like and prioritise them. We had Finlay Dane, Charlotte Grace, Jasper John and Ava Chloe. So if it was one of each it was going to be Finlay and Charlotte. As it was, we have Finlay and Jasper (born in that order).
I have met a LOT of twins and I personally don't like similar names or themes. My twins are so different but they are always mixed up and similar sounding names (or even the same letter) would only make that worse. These kids have to share everything for the rest of their lives - let them have their own names.
I now also have a daughter called Addison Grace ( funny that we didn't go with our previously chosen girls names)
List of names that we had that didn't get used - Oliver, Elliot, Xavier, Sebastion, Adelaide, Bridget, Immogen.
Good luck, its not easy but you'll get there.
Mum to twin boys & baby girl