Thank you Pam for your advice! For some reason we gravitate toward A names. The -on ending was really just a coincidence, but Cambria is really the only name we love that does not begin with an A. There are other names we have considered but we really just do not love.
Addison and Anniston would be fine for MNs but we got a wonderful suggestion on a previous thread to use Christmas themed MNs since our due date is so close to Christmas. We have not decided on the MNs yet but we really like the idea of Christmas MNs.
Aspen and Ashlyn were just ideas, but I do love Aurora. Aurora and Anniston or Aurora and Addison would be adorable.
Amaya and Alana would also work. The problem with Anniston and Addison, is the n and d sound are very close and I won't get into linguistics, but they share a same category.... so they sound very similar.
Some other A options:
Well I;m sorry you feel that way - I didn't say it to insult you, I was trying to tell you how alternative spellings are perceived by other people. And just because I am not a twin doesn't mean I don't have an idea of what it might feel like to have a very similar name to a sibling.
If you love those 2 names then use them. Period. And I would definitely use the original spelling.
I hope you find wonderful, stunning middle names. Congrats.
I don't mind twin names that are a bit match-y, but I agree with what others have posted- Addison and Anniston are very similar, similar enough to where there might be confusion. I really like the name Addison and think Addie/Addy is a really cute nn. Anniston has never been my style, mostly because of the celebrity connection. This is just my opinion, though. In all honesty, there are several names on my "favorites list" that I'm pretty sure wouldn't be popular with the nameberry community. I really believe that if you truly love a name and can sincerely envision your child having that name as a baby, child, teenager, and adult, you should use it.
In the event that you want to reconsider Anniston, here are some names that I think go well with Addison (no reason why...they just seem to match):
ETA: I forgot to say- If you do decide to use Addison and Anniston, IMO you should stick with the typical spelling.
I'm here to offer constructive criticism that I hope will be helpful to you.
I'm a college professor and recently had identical twins in one of my classes named Emily and Amelia. They always sat together and often wore very similar outfits. I could never tell the apart except on paper (their writing styles were quite different). To be honest, it absolutely drove me crazy, and I would constantly wonder to myself what kinds of parents would give identical twins matching names like that. I mentioned them to a colleague once, and it turned out she also had them in class and thought the same thing.
So the point is that while you may be a fan of similar names for twins, many people will not be, and it may in fact cause them problems later in life. Consider how their names will affect their experiences as they grow up. Clearly, you have some reservations about using these names, as you have asked about alternative spellings to differentiate them.
Finally, if you are intent on using the names you've chosen, I would absolutely use the conventional spellings for all the reasons people have already stated.
Aurora, Amaya and Alana are all lovely names, and I could see any combination of them being twins with no issues. If you're looking for suggestions, what about these (lots are similar, I've included variations etc. The ones in bold are the ones I think you'll like best)-