I also have three identical seeming patents. I was also confused, so I asked my patent examiner friend, and this was his response. I assume the same applies to you:

"You have one patent family with three patents in it. The lowest number is the parent, it was first to grant. Before it was granted a continuation was filed - they wanted to claim some shit that you disclosed in the parent but didn't claim, and it got granted. Before that one got granted a second continuation was filed to claim some shit that was disclosed in the first continuation. Sometimes that comes from realizing something else in the patent specification was also really important and deserves protection, or something comes up in prosecution and the easiest way to get around a rejection is to file a continuation. All the claims in the patent family are unique."