Yair planty of good advice.
Advice:
1) make sure you've seen one of the ladies solo before and get on well w/ each other.
2) ask her about duo partners. Make sure to articulate the general style you'd like (eg, both ladies focus on you only, or more interactive style where all play with all). The chemistry between the ladies is essential.
3) If you normally book an hour, book 90 for the duo.
4) know real life isn't exactly like what you see on porn. Know you need to change condoms between ladies. Ladies always appreciate an eye toward health. Factor that I to your plan.
5) if you have a general idea, let the ladies know. I've always enjoyed being the teammate not centre of attention so I'll say me and lady A will double team on Lady B, then after a while me and Lady B will team up on Lady A, then break out the safety gear and I'll go back at Lady B, the change the gear and finish with Lady A. Or something like that. You may have some other sense so let them know.
Enjoy!