I know of five sister sets named [name]Kaitlyn[/name] and [name]Kristen[/name] (all different spellings though; one set also has a brother [name]Eddie[/name]), as well as two sets of [name]Katie[/name] (not a nn) and [name]Victoria[/name]. Are there any sets you know more than one of?
[name]Rachel[/name] and [name]Hannah[/name]. There are a million [name]Rachel[/name] and Hannahs over here, siblings and just on their own.
[name]Nicole[/name] and [name]Danielle[/name]! I know many, mostly born in the 90’s. [name]Nicole[/name] is always older than [name]Danielle[/name] and they’re typically of French origin. I’ve also noticed a lot of Jacobs and Johns.
My girls middle names are [name]Caitlin[/name] & [name]Kirstin[/name] 
I’ve noticed the same thing but more with married couples! I know a few [name]Mike[/name] & [name]Julie[/name]'s and [name]Ryan[/name] & [name]Jen[/name]'s for example. I suppose that’s only to be expected how ever many years down the line from popular naming trends though.
I know about 5 sets of [name]Ben[/name] and [name]Tim[/name] (some as full names, some [name]Benjamin[/name] and [name]Timothy[/name]), 2 [name]Ben[/name] and Guys, 2 [name]Hamish[/name] and Andrews, 2 [name]Alfie[/name] and Barneys (both from [name]England[/name]), 2 [name]Lucy[/name] and Emmas, 3 [name]Jack[/name] and Annas, and I’m sure there are more that I can’t think of right now.
I also find that the names [name]Jordan[/name], [name]Olivia[/name] and [name]Elliot[/name] come together. I know a [name]Jordan[/name] [name]Olivia[/name] with a brother [name]Elliot[/name], brothers [name]Jordan[/name] and [name]Elliot[/name], and siblings [name]Olivia[/name], [name]Jordan[/name] and [name]Eliot[/name].
[name]Jill[/name] and [name]Rachel[/name] is a combo I’ve come across a lot.
[name]Mary[/name] and [name]Christopher[/name]
I know three different sets of [name]Alexis[/name] & [name]Erica[/name].
[name]Alexis[/name] & [name]Erica[/name]
[name]Ahlexis[/name] & [name]Erikah[/name]
[name]Alexis[/name] & [name]Ericka[/name]
[name]Rebecca[/name] and [name]Rachel[/name].
This combination always seems to go together even when they’re not twins.