Two phones appearing on android device manager

I lost my phone last month and was desperately looking for ways to track it. I never installed any apps to track it and so I got online to see if there were other options and found ‘Android Device Manager’. After the remote download, I tried locating it, but then the internet was turned off and a few days later with no success, I decided to go for the factory reset. I was talking with a friend today and he told me that, he got a call from someone saying I had given that person his number, so I decided to get on ADM to see if I could maybe track it this time or check what was going on. To my surprise, I now see two phones listed under my account. I have not bought a new phone yet. I am just wondering why does it show another phone under my account.