Having recently bought 3 books from the Amazon website, two of which were from other suppliers and delivered 10 or so days late, I logged in to check why they were late. Using my usual username and what I thought was the correct password, discovered that I couldn’t see the latest books that I had ordered, only my last batch of books bought before Christmas. What was going on? I tried again and again without success until I entered another password that I also use sometimes. This time I could see my latest three books but not my pre-Christmas orders!

Somehow I now have two Amazon accounts that share the same username but which have two different passwords. How can this be? Surely usernames should be unique!