Are u saying you have a duplicate device or you just need to rename? To insure you don't have a duplicate device, hit the arrow on the right side of the device then look at the device details. There should be a button to forget device. If you need to rename the device tap on the device then hit the pencil next to the device name. I've had different kindles on my WiFi network and they can all look like they are the same but you would need to go into the device settings to see the serial number etc and then discover it's two different devices. iPhones can show up the same.
