They only do duos if they're working out of the same incall apartment.  They won't travel to another location to do a duo.  When two girls are offering duo's it will be mentioned in their CV ad.  Right now I think there are a couple in LA (Casino and Lisa, and Sera and Terra) and one in OC, (Bomi and whoever her roommate is right now --- booker can tell you).  Your best bet might be two independent Asian girls.  I'm pretty sure Mia Hug has another Asian girl or two that she does doubles with.  Check her profile on TER for contact info.  

offered by some of the women at the palace with or without Pepsi.  You may want to check out that option on CV.

or check with LA Sera