Only one visit was required when I renounced (Amsterdam, 2015). It may vary from consulate to consulate. Have a look on the website of the consulate you have in mind - somewhere under the "Citizens Service" section. If you don't find anything useful, email them and ask.
Commonly, once you email them requesting an appointment, they'll send instructions telling you what documentation you need to prepare and how they want you to do it (send or bring).
It really does seem to vary by consulate - and even sometimes it varies between the "requirements" that appear on the consulate website and the actual practice. Safest thing might be to call the Paris Consulate (not the Embassy - that's in a separate building a block or so away) and just ask about the "two appointment" requirement.
Generally speaking, the State Dept. employees at the consulates tend to be reasonably sympathetic to those looking to renounce (perhaps they'd like to do so themselves!) as long as you start out your conversation in a "friendly" tone of voice.
In London it was one appointment in 2016 and still is. I know someone who just renounced last month, one appointment. and I have to say that the embassy staff were very helpful and professional at my renunciation appointment. no questions asked at all. just went through the motions professionally.