I had two recent experiences on Plenty of Fish that were nearly identical. I got an e-mail from a guy with the screen name "LegalbriefsNV". I immediately recognized the screen name and picture as a guy named Ron who had contacted me on match.com a few months back. He wrote me saying he liked my profile, and would like to get to know me. Now I don't use the same pictures on both sites, but they are similar enough that one should be able to tell I am the same person. This was embarrassing as Ron clearly didn't know we'd gone this route before. We had e-mailed back and forth a handful of times on match.com and suddenly he stopped responding. I thought about it a few days, then decided to respond to him and make a joke about it. I responded to his POF e-mail saying "Hey, this is funny but we've met before!". I explained about match.com and asked him why he'd stopped writing. He wrote back asking if he could have my cell number. He thought if we texted each other, there would be less chance of losing contact again. I sent him my number, and he did indeed text me a few times. Each one was something random and creepy like "hey gorgeous" or "hi there pretty girl". After a few days, he disappeared again. As a strange aside I'd like to point out that on match.com he listed his age as 37.. on POF he listed it as 43. That's a good size gap, and you'd think someone would know their age! See ya, Ron!
Next guy did the same thing. I got an e-mail on POF from a guy named Chris going by the screen name Coz42. Again I recognized the screen name and profile pic from match.com. Chris had been e-mailing me on match maybe a year or two ago. It ended the same way, a bunch of e-mails, things going well.. then a sudden disappearance. He wrote to me on POF as if he'd never met me before. This time I decided that enough time had gone by since our match.com meeting, that I didn't need to bring attention to it. I'd remembered liking him, and having a bit in common. I wrote him back once or twice, then he again disappeared. I see he's still active on both sites, but I will only give someone two shots before I move on. Bon Voyage, Chris!