COM port list entry duplication

[mickabrig7]

Summary :
The list of available COM ports shows the same port 2 times under certain conditions.

Steps to reproduce :

1. Plug in a board (Teensy in my case)
2. Open software
3. Connect to the board
4. Unplug and replug the board
5. Go back to the Serial Connection window
6. The board's COM port now appears 2 times in the drop-down list

Possible fixes :

• Check the board status when opening the Serial Connection window