update : It is not needed to restart/close Eclipse
As told in comments by Ved Praksh, the solution is:
Exit Eclipse
End all adb processes from task manager as well.. Then:
In cmd, adb kill-server --> adb start-server --> adb devices
Then restart eclipse.
Most probably it will show only one device this time.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…