It’s better just to bang them back to back, because they are NOT going to both blow your dick at the same time. One girl won’t eat the other girl out while you’re banging. Basically you will be paying twice the price and condense your time frame and not get a true threesome. They will want you to fuck one first then pull out change condom and fuck next one, basically paying double to bust one nut. That’s why I would just bang one for half an hour then send the next one in the room for the next half hour. Just my opinion