I am indifferent on this, actually.
I see how they're different but I also see the huge similarities
If they went by Ari and Brie then it's not bad, but just seems strange to me that they both have -anna.
I LOVE the idea of baby A has an A name and baby B has a B name, that's cute!
Adam and Brianna is a cute sibset for boy/girl
Adam and Aaron go nicely too...although to me Aaron/Erin is pronounced EXACTLY the same air-in. I've heard it on both girls and boys (I'm in the US, CT).
Suggestions for A & B names:
Aubrey
Angeline
Antoinette
Amber
Bianca
Bethany
Brittney
Bella
Andrew
Anthony
Alexander
Brett
Bentley
Benjamin
PS - Please don't use Brian and Brianna lol although it'd be funny that's more or less the SAME name!
***Also, please consider the fact that baby A is typically first born and in school they go alphabetically so that if their name starts with A they'd again go just before their twin. Not a huge difference, but might be worth pointing out. Food for thought