It's all part of the dance. Whilst on an online date, you can talk about things that are made mention of on the website, but you cannot bring up the actual website, directly or indirectly. If one of you slips and makes mention of the website, the other must pretend they didn't hear and hastily change the subject. To come right out and talk about other dates you have been or are planning to go on is sheer dating suicide. To confuse your potential suitor for another online candidate is kamikaze territory (aren't you the one who has a sister in Iceland? No? Are you sure?)
It's best to feign ignorance of the whole world of online dating. That way you can keep up the pretense that you both met randomly, and just happen to know each other's life history/taste in music/career plan by sheer coincidence.
Of course, if the date is not going well and you want to put off your potential suitor, then it makes sense to talk about nothing but online dating. As in, the number of years you have been online dating, unsuccessfully; an extensive rundown of how many online dates you have been on previously; the picture you once put up on your profile of you in your underwear in order to garner more dates, etc.