What would be the most tactful way of inquiring whether multiples are ok?
A representative from an agency acted insulted by the question and I understand about explicit questions but if you don't ask.
I have had more luck with some agencies as long as it was within the time that was agreed upon.
I've had some independents that were expecting me to leave as soon as the deed took place which sometimes can be within the first 10 to 15 min.
How would you word it?

If it's important enough, then don't see any providers whose profiles don't say "multiple pops allowed." Of course, you can only see that if you're VIP, but, like I said, if it is important enough, it should be worth the price.

ike Josephine said check their reviews. If you want to be sure - first verify with them and them ask if u can ask a discrete question. If they say yes ask if they offer re fills on their cups of coffee. They shouldn't mind answering that....or you could just see me.... I offer that.

and just treat every session as YMMV and just see what happens. That way you aren't disappointed by too high expectations which can ruin an otherwise great session. If things aren't what you had hoped for, don't see that girl again. I want minimal premeeting contact, the less said the better ime.

I believe that most TER advertisers offer dates based on TIME only, and whatever happens in the allotted time happens.  That being said, many also will use the term "MSOG" which means "multiple shots on goal".  The thing to remember is that while you may be free to try for a second or third "shot", there's no guarantee that it will happen.  Just enjoy the experience and don't worry about keeping score.