Wow! I have a Fitbit Alta HR that I've had for a couple of years. I only sync it to my iPad at home (I only have a Tracfone so I didn't bother with the app for a phone). So far it seems to only have paired with my iPad.
That's really strange though. I wonder if the other account it was trying to pair with is similar in some respect. I remember using my auto key fob to open what I thought was my car door. It worked but when I was going to get into the car, I saw all these stuffed animals on the back windshield ledge. I thought what the heck, then I realized it wasn't my car!!!
I closed and locked the door real fast! I guess it was because it was the same model car with the same code!
Kathy