There are 2 boards with the same ID sipeed-longan-nano.
Is this normal?
Is it possible to change the ID? Or to delete one?
I need the ID to be unique for a utility I use (cargo-pio).
A board is only unique per platform. There are multiple platforms implementing different features (such as available platforms) for this board, and that is OK from the PlatformIO side, since it only searches the boards of the referenced platform = .. value in the platformio.ini.