I use \"adb devices\" to get following result. Only one device is connected to PC by USB, but we get 8 lines of result.
Could anyone suggest the reason?
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I had the same issue and none of the other answers worked. It seems to occur frequently when you connect to the device using the wifi mode (running command 'adb tcpip 5555'). I found this solution, its sort of a workaround but it does work.
This process is a little lengthy but its the only one that has worked everytime for me.