I've asked around the girls who would be interested in doubles sadly it very hard to get 2 who are interested to be roommates with each other. Price usually around 7 to 10 Benny for an hour not including tips, depending on the studio. If you guys willing to splurge, honestly its probably less work for the girls but more awkward. That said those of you that are catholic getting 2 catholic girls at once is pretty amazing and alot less hassle changing caps in between girls going back and forth.
Intel so far YMMV
SF/SG
Velvet willing, her roommate Boa is not
Gia willing
julie willing but i dont think they are in the same apartment anymore
I wasn't interest in Soyeon, cat or virgin enough to ask.
AS
Dami willing, jinah was off on New years eve i offered her double the usual price as a new years eve special she was not down. considering double the price and half the work its like 4x pay if shes not down its a hard no for doubles.
Jinah not willing
lani not willing
lily willing, yuna was not