[name]Caleb[/name] [name]Emmett[/name] and [name]Noah[/name] [name]Alexander[/name] - I think [name]Caleb[/name] and [name]Noah[/name] are perfect for twin brothers, and I have to say, I adore [name]Caleb[/name] [name]Emmett[/name]! Two of my favorites, and they’re so lovely together. 
[name]Willow[/name] [name]Maeve[/name] and [name]Violet[/name] [name]Ada[/name] - [name]LOVE[/name] [name]Violet[/name], and I like [name]Ada[/name] with [name]Violet[/name] (or even an [name]Addy[/name] name–I think [name]Violet[/name] [name]Adeline[/name] would be so charming! [name]Ada[/name] almost seems too short–I would either swap it to [name]Ada[/name] [name]Violet[/name], or do a longer [name]Ada[/name] name, like [name]Violet[/name] [name]Adelaide[/name] or [name]Violet[/name] [name]Adeline[/name]). [name]Willow[/name] and [name]Violet[/name] are lovely together, but almost seem too matchy to me.
[name]Holly[/name] and [name]Declan[/name] - I like [name]Holly[/name] [name]Florence[/name] better than [name]Holly[/name] [name]Ethel[/name], but I’m honestly not a fan of either. I like something that would probably be classified as a modern classic–like [name]Juliana[/name]-- with [name]Holly[/name]. I [name]LOVE[/name] [name]Declan[/name], though, but I think something like [name]Violet[/name] would pair better with it than [name]Holly[/name].
As for me, I highly doubt I would go in search of twin names. I know enough twins to know that a lot of them don’t like having matchy names, they want to be their own person. So I wouldn’t give twins (or triplets, or quads) names any different from what I would name 2, or 3, or 4 singletons in a row. So by that reasoning, at this point in my life, pairings would be:
[name]Isabelle[/name] [name]Aurora[/name] [name]Grace[/name] and [name]Arianne[/name] [name]Eleanor[/name] [name]Kate[/name] “[name]Bella[/name] and [name]Ari[/name]”
[name]Isabelle[/name] [name]Aurora[/name] and [name]Caleb[/name] [name]Elias[/name] [name]Joseph[/name] “[name]Bella[/name] and [name]Cal[/name]/[name]Caleb[/name]”
[name]Caleb[/name] [name]Elias[/name] [name]Joseph[/name] and [name]Everett[/name] [name]Joshua[/name] [name]Charles[/name] “[name]Cal[/name] and Ev”
Although if I had boy/girl twins, I would be hard-pressed not to name them [name]Isabelle[/name] ([name]Aurora[/name] [name]Grace[/name]) and [name]Avery[/name] ([name]Ian[/name] [name]George[/name])–I’ve been in love with that as a sibset for years now! I think it would be so cute to meet twins with those names. 
If I went by current crushes, though, I’d probably end up with:
[name]Annabel[/name] [name]Sophie[/name] [name]Rebecca[/name] and [name]Samuel[/name] [name]Ephraim[/name] [name]Jack[/name] “[name]Annie[/name] and [name]Sam[/name]”
[name]Annabel[/name] [name]Sophie[/name] [name]Rebecca[/name] and [name]Eleni[/name] [name]Giovanna[/name] [name]Kate[/name] “[name]Annie[/name] and [name]Leni[/name]”
[name]Samuel[/name] [name]Ephraim[/name] [name]Jack[/name] and [name]Charles[/name] [name]Oliver[/name] [name]Darcy[/name] “[name]Sam[/name] and [name]Charlie[/name]”