For quite a while every time Firefox thinks it sees any sort of variation in an autofill address, it has asked if it should change the saved address or save a new address (I have complained that it lacks a Do Nothing choice). In the past I have usually just ignored this prompt when I didn't want it to do either and usually it has been ok. Every once in a while however, Firefox just decides to create a new saved address without my telling it to and without telling me about it. Then on some future website when I go to fill out a form, I will suddenly find that I have what look like duplicate choices because Firefox only shows the list for the current field plus a little more data which may or may not show what is different. The most recent instance, Firefox created a duplicate of my name, address, email, phone, etc. The only difference was that the new address included data in the Organization field. It took me while to notice it because most online forms don't have anywhere for the Organization to go. I only noticed the extra address when Firefox used it as part of my mailing address when I placed an order online. Then I had to think to figure out where Firefox had gotten that 'Organization' -- I realized that I had typed that phrase on a website form a few days earlier, but certainly not in any field labeled "Organization" and I certainly didn't tell Firefox to save it. I need to use autofill to fill out online forms -- There are several forms that I fill out once a day, but I also use autofill to fill in my name and address on a lot of other online forms where occasionally I need to type in some of the data. This seems to be when Firefox just decides it ought to keep whatever it saw me type. I like Firefox and have it as my default browser, but I have noticed that Chrome and Opera both do a better job of filling out online forms